Conventional elements in architecture represent one stage in an evolutionary development, and they contain in their changed use and expression some of their past meaning as well as their new meaning. What can be called the vestigial element parallels the double-functioning element.
It is distinct from a superfluous element because it contains a double meaning. This is the result of a more or less ambiguous combination of the old meaning, called up by associations, with a new meaning created by the modified or new function, structural or programmatic, and the new context. The vestigial element discourages clarity of meaning; it promotes richness of meaning instead. It is a basis for change and growth in the city as manifest in remodeling which involves old buildings with new uses both programmatic and symbolic (like palazzi which become museums or embassies), and old street patterns with new uses and scales of movement. The paths of medieval fortification walls in European cities became boulevards in the nineteenth century; a section of Broadway is a piazza and a symbol rather than an artery to upper New York state. The ghost of Dock Street in Philadelphia's Society Hill, however, is a meaningless vestige rather than a working element resulting from a valid transition between the
old and the new. I shall later refer to the vestigial element as it appears in Michelangelo's architecture and in what might be called Pop architecture.