The Maison Carrée, finished in the early years of the 1st century AD, is the only Roman temple still complete on all sides — pediment, columns, walls, roof. Its proportions are perfect: a Corinthian portico with thirty fluted columns on a high podium, the whole building no larger than a comfortable house. Thomas Jefferson, who saw it in 1787, declared it "the most precious morsel of architecture left us by antiquity" and used it as the model for the Virginia State Capitol.
Inside is a digital film telling the city's Roman story. It's a quick visit but the building itself — small, sharp-edged, white in the Mediterranean light — is the point. Walk around it slowly. The Carré d'Art across the square, a contemporary art museum designed by Norman Foster, deliberately echoes the temple's proportions.