Quod significat: Vitruvius' ultimate criterion for (good) architecture.

This article analyzes a complex passage from Vitruvius' *De Architectura* (I, 1, 3), focusing on his concept of signification in architecture, which involves a "signifier" (the design and construction) and a "signified" (the proposed building or intended use). Unlike Quintilian’s rhetorical model, Vitruvius’ approach aligns more closely with Stoic philosophy, particularly Chrysippus, but omits the third element, the *tynchanon* (the actual physical object), likely because Vitruvius addresses architectural designs rather than completed buildings. The paper argues that successful architecture occurs when a building’s form, created according to established principles and tradition, effectively conveys its intended purpose to the community, enabling public recognition of the building’s identity before and after construction. This process of signification depends on both form and use, with use often playing a decisive role in how buildings are perceived over time, as illustrated by historical examples such as the Parthenon’s transformations. Ultimately, Vitruvius views good architecture as the realization of a building’s intended identity through design and erection that aligns with communal expectations and disciplinary knowledge.