# The Function Is Temporary
The Colosseum's last gladiatorial games were in 523 AD. After that, the building was stripped for stone, converted to housing inside its arcades, occupied by the Frangipane family as a fortress in the twelfth century, received a papal installation of Stations of the Cross in 1750, and has been a tourist site ever since. Not a single use since the fifth century resembles what the building was designed for.
Functionalism would have demolished it in 524.
This is the category error at the center of modern design. The theory says: design for the use. But uses change. Programs expire. Industries relocate. Demographics shift. The building remains. A building designed only for its current program is, by definition, designed to become obsolete.
The Colosseum is still there because it was not designed for a program. It was designed as a type. The distinction is everything.
Program vs. Type
A program is a list of functional requirements: this building must seat 80,000 spectators, provide 76 entrances for crowd egress, support the weight of awnings, and contain the arena floor at a specific dimension. A program is a snapshot of a moment's needs.
A type is something different. A type is a structural pattern that encodes the solution to a recurring problem in a form general enough to survive the specific uses of any particular moment.
The basilica is a type. It originated in Rome as a public hall for commerce and legal proceedings: a long rectangular nave with side aisles, clerestory windows for light, an apse at the end where the magistrate sat. Early Christian communities adopted it as a church format because it matched their needs perfectly, without a single modification. The same type became a courthouse, a covered market, a railway terminus, and a concert hall. The basilica type is now over two thousand years old and still in use. No single basilica was designed for all of these functions. The type was flexible enough to absorb them all.
The courtyard house is a type. It originated independently in Mesopotamia, Egypt, China, Rome, and across the Islamic world: a building organized around a central open court, rooms on multiple sides, single controlled entry. This type has been a private home, a workshop, a caravanserai, a school, a hospital, a law firm, and a hotel. The structural logic accommodates all of it. The type was not designed for any of these specific uses. It was designed for the recurring problem of organizing a building around light, air, and controlled access.
What makes types durable is that they encode the deep structure of a recurring problem, separated from any particular solution. Programs are specific. Types are general. Programs expire. Types persist.
The Ghost in Lucca
There is a piazza in the center of Lucca, in Tuscany, that has an unusual shape. It is elliptical. The buildings around it follow the curve without obvious reason. Pedestrians walk through it without knowing anything is wrong.
Underneath them, encoded in property lines and building footprints, is the outline of a Roman amphitheater from the first or second century AD. The stone was quarried away over centuries for other construction. The structure vanished. But the ellipse of the seating arrangements shaped the medieval plot divisions, and those divisions shaped the buildings built on top of them, and those buildings shaped the space that pedestrians walk through today.
The physical structure is gone. The form is not. The city retained the pattern without the material, without the function, without any conscious decision to preserve it. It survived as geometry encoded in property ownership.
Aldo Rossi called these accumulated forms "urban artifacts." They are the physical record of collective decisions accumulated over centuries. They survive not because anyone chose to preserve them, but because forms, once encoded in a city's structure, are remarkably difficult to dislodge. The ellipse in Lucca survived the fall of Rome, the medieval building campaigns, the Renaissance replanning, the modern era. It is still there.
The Functionalist Mistake
Urban renewal in the mid-twentieth century was functionalist at its core. The planners looked at old neighborhoods and saw outdated programs: buildings designed for industries that had moved, street grids sized for foot traffic and horse carts, housing built before indoor plumbing. They concluded the correct response was replacement.
Pruitt-Igoe in St. Louis was the result: 33 high-rise towers designed for a specific program, constructed in 1954, demolished in 1972. Eighteen years. The mixed-use neighborhood it replaced had functioned for a century.
The same pattern repeated across every American city. The planners classified neighborhoods as blighted based on building age and income levels. The residents classified them as home. The planners won. The communities dispersed. The replacement towers failed, almost without exception, within a generation.
Herbert Gans documented the West End of Boston in 1962 as its demolition was occurring. His finding was precise: by every functional measure — crime rates, employment, social cohesion, community organization — the neighborhood was working. The buildings were old. The community was not. The planners could not see the difference because their instruments measured programs, not types.
What the cleared neighborhoods had and the replacement towers lacked was accumulated typological richness. Not aesthetics. Not sentiment. Working structural patterns developed over decades of use, modified by residents to fit actual life, embedded in fabric that could absorb the next change. The towers had none of this. They were programs. When the program failed, nothing remained to absorb the failure.
The Protocol Is a Type
Software has its own version of this argument.
A software program is written for a specific use case. It encodes particular assumptions about how the problem is structured, what the user wants, what the system looks like underneath. When those assumptions change, the program must be rewritten. Most software lives for a few years. Rewriting is constant.
But the internet runs on protocols that are decades old. TCP/IP was formalized in 1981. HTTP/1.0 dates to 1996. The core email protocols are older than most people working in technology. These are types, not programs. They encode the deep structure of the communication problem — how packets should be addressed, routed, reassembled — without specifying any particular implementation.
Every email client is a program. The SMTP protocol is a type. Programs come and go. The type persists.
What makes a protocol a type is the same quality that makes the basilica a type: it solves a recurring structural problem at the right level of abstraction. Specific enough to work. General enough to be reused. Not designed for any particular implementation, but capable of hosting any implementation that fits its pattern.
The same distinction applies to legal frameworks, agricultural varieties, musical forms, and organizational structures. In every domain, the things that last are the ones that encode structural solutions at the right level of generality. The things that fail are the ones designed for the specific conditions of a particular moment.
What Collective Memory Is
Rossi called the primary elements of a city — its great monuments, its persistent types — the physical substrate of collective memory. Not as metaphor. As a literal description of what these forms carry.
The piazza where a community has gathered for five hundred years to celebrate, mourn, and constitute itself is not interchangeable with a new plaza that provides equivalent square footage. The accumulated weight of collective use is transmitted physically. You can feel a space that has been the site of meaning for generations; you cannot manufacture that feeling by optimizing the material conditions.
When urban renewal demolished this accumulated substrate, it did not just destroy buildings. It destroyed the physical record of how a community had organized itself over time. The replacement towers had no memory. They could not have it. Memory accumulates; it cannot be installed.
Robert Putnam documented a collapse of social trust and civic engagement in the United States from the 1960s onward. He traced it to suburbanization, to television, to the dissolution of civic institutions. All of these are real. But there is a physical dimension too: we systematically demolished the built substrate in which social trust accumulates — the corner bar where three generations had drunk together, the piazza where every family had celebrated something, the street that everyone knew — and replaced it with forms that had no such history and could not develop one at the speed the new development required.
The functionalist city has no memory. That is not a poetic complaint. It is a description of a functional failure. Memory is not decorative. It is the material condition for belonging.
The Implication
The argument for types over programs is not an argument for preservation over development. Cities change; buildings should change. The question is what structure you build for change to occur within.
A city of programs is a city perpetually demolishing and rebuilding — each cycle starting from zero, each new building designed for uses that will have changed before the building finishes depreciating. The knowledge embedded in the previous building is destroyed. The accumulated typological fitness of the previous neighborhood is lost. You pay the full cost of construction each time and recover none of the value of what was there.
A city of types is a city that can change its uses while retaining its structural intelligence. The basilica does not need to be demolished to become a library. The courtyard house does not need to be cleared to become an office. The type absorbs the new function because it was designed at the right level of generality.
The practical question is not whether to preserve old buildings. It is whether to commission types or programs. A building designed as a great type — a structure that encodes the solution to a recurring problem in adaptable form — is an investment in the city's capacity to absorb change without starting over. A building designed only for its current program is a liability that begins depreciating at the moment of occupancy.
The Colosseum is still there. Pruitt-Igoe lasted eighteen years. The difference is not age. It is whether the form was built to outlast the function it was first given.