Essay on Circulation

Considered in the abstract, outwith this particular disciplinary context, the word circulation immediately suggests the idea of movement; if we think, for example, of blood or lymphatic circulation, we refer to the phenomenon of the movement of liquids inside the organism—blood, lymph—required for tissue renewal and therefore crucial for their survival. In architecture the concept is not that different; obviously it refers to the movement of people inside a space, the built organism, needed to make it work and therefore to survive.

The first, and most simple, definition of circulation in architecture concerns a functional issue: how to enable the movement of people from one space to another, from one floor to another. This is followed by how this sort of displacement can be achieved in a logical and rational manner, preserving the integrity of the spaces considered primary. This is why circulation spaces are sometimes regarded as accessory spaces, spaces between other spaces, useful only for the life of the main spaces and simply there to serve their primary function of connecting.

Circulation is clearly much more than that, however. First and foremost it is where the physical experience of space takes place; it is the place in which our bodies become aware, in space and time, of the built dimension of the environment in which we are (the promenade architecturale).

It is the place through which the space is revealed in a narrative sense. Through movement, the perception of the space changes, its tale takes shape; the space can be lived in three dimensions along the horizontal, vertical, or sloping connections. It is the place where the emotional perception of architecture takes place.

Circulation spaces can also be social spaces. To use Aldo van Eyckís metaphor of the house being like a small city1, circulation spaces can be compared to public spaces such as streets or squares. They are the places where we meet, the places where we walk and where we spend time, the places where we socialize. In this sense, circulation is also the place for creativity and invention because, unlike formalized spaces, it has an open dimension, in its use and in its interpretation.

Moreover, circulation is what structures and brings together the different parts of a building. Just as the system of streets and squares structures and gives shape to the urban environment in historic cities, in buildings the circulation structures and organizes the available space. Circulation thus represents one of the essential invariants of architecture.

Lastly, circulation defines and regulates the relationship between the building and its surroundings, between architecture and context.

It has an anomalous H-shaped plan, with two flanking wings that project beyond the main façade This architectural type was more commonly used in suburban villas, the scheme for which was consolidated by Peruzzi’s Villa Farnesina onwards. Clearly the particular situation of the palazzo, on a natural slope at a significant distance from the Strada Felice (now the Via Sistina) and Piazza Barberini, must have induced Maderno—as the historian Rudolf Wittkower believes—to adopt such a scheme, rather than that of a city palace.3

The importance of this design, besides the various  innovations introduced into the language of the main façade4 and the unusual layout of the plan5, resides in the relationship that it sets up with the garden at the back and in the solution proposed for the differing heights of the surrounding land.

Let us go in: after crossing the external space framed by the two side wings, the palace is entered through a deep portico that characterizes the entire base of the entrance façade. The exedra is reached through two rows of columns, after which we find ourselves in the oval space with the stairs leading to the first floor. Continuing along the axis, we find ourselves outside again, at the beginning of the long ramp that cuts the garden at the back in two. The building is thus porous at ground level, allowing visitors access to the ramp in the garden, where the real entrance to the edifice is found. Only after crossing the entire building on the ground floor and walking along the long external garden ramp, can one turn back in order to directly access the piano nobile on the floor above. It is these movements and changes of direction that cancel out the monumentality of the building to reveal its most private space, the garden and its residential façade.

The sophisticated circulation inside Palazzo Barberini brings the topography of the site into play and sets up an intimate relationship between architecture and landscape in an original system of relations. The garden ramp, a metaphor for the street, becomes a device that contrives to anchor the building to the place.

Take for example, Palazzo Sanfelice, which he built between 1724 and 1728 for himself and his family in the Sanità district of Naples. The staircase is so imposing that it stands out as a construction in its own right, concluding the fourth side of the main courtyard. It becomes the perspectival backdrop of the courtyard, and also allows the eye to travel across it, revealing the greenery behind it.  

On entering the palazzo, the sequence of spaces becomes clear; from the relatively narrow and therefore somewhat dim Via Sanità, one crosses the dark threshold of the great portal that leads to the main courtyard. This is a shared space, again external and brightly lit. Across the courtyard at the back, is the staircase, which starts off as a single ramp and then splits off in two opposite directions, orthogonal to the entrance. The staircase is again an outdoor space, but a covered one, through which the garden can be seen at the rear.  

The architect thus defines a series of thresholds through which the public city space, the street space, becomes increasing­ly intimate, gathered in, and private. By means of a series of spatial devices, the architecture organizes the transition. In this system, the staircase becomes an essential junction, conceived as a natural extension of the public space, it is con­figured like a diagonal street, providing natural access to each apartment. Thus Sanfelice’s staircase carries greater significance than mere function. The staircase becomes a meeting place, a place for socializing; a new architectural space.  

Another, no less significant, example is the Reggia di Caserta. Here the public circulation system becomes a fundamental element for the structure of the space. Thanks to the connections, this geometric, monumental, and severe building empties itself, is interrupted, is articulated in a new synthesis of classicist rigor and scenographic conception of space. There is no doubt that the logic of Vanvitelli’s designs is drawn from the great Imperial residences, first and foremost Versailles, the Louvre, the Escorial, and Inigo Jones’s projects for Whitehall Palace. We are clearly in this tradition. Yet, as Wittkower notes, “None of these great residences, however, was designed with the same compelling logic and the same love for the absolute geometrical pattern, characteristics which have a long Italian ancestry and reveal, at the same time, Vanvitelli’s rationalism and classicism.”7  

Furthermore, “But in one [another] important respect Caserta is different from all similar buildings. Vanvitelli had been reared in the scenographic tradition of the Italian Late Baroque, and it was at Caserta that the scenographic principles were carried farther than anywhere else.”8 

Immediately on entering the Reggia palace building, the importance of the connections and the views is manifest. The first two courtyards on the diagonal axes are visible from the entrance vestibule on the ground floor, and ahead is the very lengthy monumental gallery that runs the whole depth of the building. A sort of internal portico sections the building, connecting the public entrance on one side and the private gardens on the other. The four internal courtyards that structure the complex from one single spot, as in a panopticon, are visible from the central vestibule, at the intersection of the four internal arms. The great ceremonial staircase, rigorously composed at right angles, begins here and leads to the first floor, where a second octagonal vestibule, corresponding to the one on the ground floor, opens into the state apartments and the palace chapel.  

The views from the great staircase are fascinating and surprising. It seems to be within one of Piranesi or Bibiena’s fantastical visions. The light, spilling in from all directions, makes it feel as though one is not inside a building. The size and width of the stairway and its incline suffice to make it feel like a sort of great sloping street connecting the courtyard with the first floor. The public ground floor space thus extends and continues seamlessly on to the first level, connecting all the state apartments within the complex. 

There is more: crossing the building diagonally, the ordinary perception of the built space is called into question. Generally speaking, we are used to moving around inside buildings horizontally—in front, behind, right, and left. This sort of space is largely two-dimensional. The third dimension, the vertical one, is generally reserved for the use of stairs or elevators, places or devices specifically dedicated to going up or down. The use of ramps provides a different movement: the one in diagonal. This is the only way to truly experience the three vertiginous and emotional dimensions of space.  

Let us resume our promenade architecturale of the house. On the first floor, the ramp continues outside. Its task of sectioning the architecture is over. The ramp, the physical manifestation of the composition’s axis of symmetry, also marks the threshold separating inside from outside. The fact that our walk takes the same route even outside the building shows the significant correspondence between the inner and the outer space. The natural landscape permeates and becomes part of the architectural landscape and vice versa.  

As we carry on walking, our gaze penetrates through the large windows, revealing the internal spaces, and through the horizontal apertures onto the surrounding landscape. In this sequence of photographic diaphragms, the final image is the most symbolically powerful. The pure landscape in the distance, perfectly framed by the aligned window, appears immediately in front of us, at the end of the promenade: a landscape ripe for contemplation, through the rational and orderly human eye.

Modeled on Hertzberger’s 1967 blueprint for the city hall in Amsterdam City Hall the Centraal Beheer is made up of fifty-six 9 × 9 meter spatial units—which the architect called “basic spatial units”—their size determined as being suitable for accommodating various different sorts of use, from work­spaces—3 × 3 meters—to meeting rooms and collective spaces. Each unit is uniform in shape but flexible and multipurpose. The workspaces are identified not by the division of a larger space or the aggregation of individual spaces, but are the basic building block in the structure of the overall space.  

Most of all, the Centraal Beheer is a project for a village10, a scheme that starts with the simple aggregation of a basic module and culminates in an urban organism made up of streets and squares, bridges and terraces. Herein lies the great merit of the Centraal Beheer, in the empty space in between the modules-building, in the circulation system that extends to become a structure in its own right, made up of voids.  

Thus the huge central circulation area, in which the space develops both vertically and horizontally, calls to mind—as Hertzberger says—the dense, complex fabric of a medieval city, a system of internal streets, which, as in cities, is lit from above by skylights. Every corner provides a space in which people can have coffee, hold an informal meeting, or simply wind down from work stress.  

We are especially interested here in the role of circulation. To start with, we need to distinguish between horizontal and vertical circulation. The horizontal connections develop freely in the system of volumes that host the different activities in an interstitial space reminiscent of a medieval street carved out of the various volumes-building. To underscore this metaphor of the street, the inner façades of the different volumes-building preserve the same character as the outer façades. Vertical circulation, however, always takes place inside hollow volumes or walls, enlarged to house staircases and ramps. Large apertures mean that the system is part of the overall space, providing constant unexpected views.  

The clever stratagem of the hollow volume not only applies to the staircases or vertical connections, it extends conceptually throughout the entire complex. It is a necessary expedient for elevating the geometric arrangement, allowing it to coincide with the structural reality.  

Kahn wrote about the project: “In the assembly I have introduced a light-giving element to the interior of the plan. If you see a series of columns you can say that the choice of columns is a choice in light. The columns as solids frame the spaces of light. Now think of it just in reverse and think that the columns are hollow and much bigger and that their walls can themselves give light, then the voids are rooms, and the column is the maker of light and can take on complex shapes and be the supporter of spaces and give light to spaces. I am working to develop the element to such an extent that it becomes a poetic entity which has its own beauty outside of its place in the composition. In this way it becomes analogous to the solid column I mentioned above as a giver of light.”13

Let us now consider the system of connections within the building in greater detail. We begin with the large entrance hall, which takes shape inside a square-plan volume. A system of diagonal walls, containing the staircases, defines the first of the spaces-within-spaces that characterize the entire project. The result is a rhomboid-shaped space, its sides defined by a system of double partitions that contain the stairs and delimit the horizontal landings, while the center remains empty all the way up, thus allowing for continuation along the axis. The interior corridors circle around the great octagonal assembly hall. Moving around this central nucleus, sudden views over the surrounding landscape appear, at the points where the volumes-building around the assembly chamber are interrupted. The walls of the chamber are also double, in order to house all the vertical connections and the horizontal distribution system.  

On the other side of the entrance vestibule, before the prayer room, there is a second volume—cylindrically shaped this time, also for circulation purposes. The role of this nu­cleus, which balances that of the entrance, serves to create the requisite distance between the assembly and the prayer room. The nucleus becomes a symbolic place that is not merely required to achieve the correct relationship between the various parts of the composition, but it also largely underscores and confirms the primary role assigned to the circulation system. Here, more than in any of his previous projects, Kahn attributed symbolic values to the connections: the connection as a necessary way of getting to grips with the architectural space, an initiatory pathway to democracy, a metaphor for the effort required to gain knowledge, an image of humanity in movement.  

Kahn’s desire to come up with a more informal dimension shines through in this concept, his desire to build this necessarily institutional architecture on a human scale.

Now for an analysis of the design. From the outside, the building looks like an imposing, suspended, mute 120 × 70 meter parallelepiped, supported externally by fourteen pillars and internally by four rows of nine pillars each. The outer walls of reinforced concrete are completely blind, and look like a continuous trabeation, a wall beam that envelops the building on all four sides of the perimeter, concealing the teaching spaces. The indoor lighting is provided only from above, from the huge coffered ceiling, also made of concrete. In contrast to the severe and closed look of the top trabeation, the lower part of the building is completely open and transparent. There is access from all sides, as it is a building with literally no doors or gates.

The nucleus of the project is the great covered full-height piazza on the ground floor, lit from above, onto which all the main rooms face: the classrooms, the library, the offices, and the laboratories. Conceived like an extension of the public city space, the sloping ramp starts in this great arena, rising to serve the various levels. 

The ramp is much wider than usual, exaggeratedly so. This simple observation completely alters its role and its significance. The fact that its size has been excessively enlarged makes it not just a circulation device but an actual space; a sort of sloping piazza, a relational space that allows people to move between one floor and the next, also conceived for pausing and interacting. The ramp becomes a dynamic place that achieves total continuity between the outdoor space of the surrounding garden and the interior, a device that amplifies and affirms the basic assumption underlying this architecture, created under the banner of openness, transparency, and freedom!  

That’s not all. Artigas’s great ramp at the Faculty of Architecture points to a new direction and possibility for architecture. This entails overcoming the notion of horizontal space as the limit of architecture. The great sloping surface signifies exactly this: the possibility of conceiving space in a different way: all is space and all is circulation, with no distinction. Just as there is no longer any distinction between the different levels of the building, because the space is continuous.  

A great revolution. 

Francesco Isidori