This chapter presents the landscape of ancient Trimithis, a polis in the fourth century AD, and a synthesis of its urban layout. The settlement extends over an irregular area in which moving sand dunes determined living spaces and the availability of water. Archaeological evidence attests the presence of a settlement at least from the Old Kingdom below the central hill on which the temple of Thoth stood from the New Kingdom to the Roman period. Our knowledge of the settlement life, history, and layout is still incomplete,but the fourth-century AD phase allows some comparisons with other cities of the Empire. The study of the buildings visible on the surface, of the excavated areas, and of the street layout suggests an imperial regular pattern of streets, with impressive public buildings like the thermae. The layout and architecture of Trimithis as they appear today resemble in several aspects the later Islamic medieval settlements of the oasis: vernacular architecture, compact organization of space, high density of buildings, labyrinthine layout, shaded or semi-shaded streets and alleys, sometimes closed with doors, and a certain disposition to close spaces to avoid exposure to sun and winds.