Ruins of the Parthenon, seen from the southwest corner, at the Acropolis, Athens, Greece
The Parthenon, Athens — completed in 432 BC and still the most influential building ever constructed. Every horizontal surface curves imperceptibly upward, every column tapers and leans inward by fractions of an inch — a structure of calibrated imperfections engineered to look geometrically perfect from every angle. © Laurens R. Krol, CC BY 4.0, via Wikimedia Commons