Ostuni was known historically as "White City" because of its small white houses, typical of Mediterranean architecture. The city is situated on the coast of the Murgia hills.
In the historic center of Ostuni, and especially in the Terra quarter, there are buildings of architectural importance: the Church of St Maria Maddelena, Palazzo Ducale, the column di St Oronzo, the Sanctuaries of St Oronzo and St Biagio, the Church of the Annunziata, the Cathedral of Ostuni with the Bastions of Aragon. The harbour of Villanova are also worth visiting. Ostuni is the second most important center after Brindisi.

the so-called "Old Town" is Ostuni's citadel build on the top of a hill and still fortified with the ancient walls. Ostuni is reputed an architectural jewel, and is commonly referred to as "the White Town" ("La Città Bianca", in Italian) for its white walls and its typically white-painted architecture. A monument on its own, the town's largest buildings are the Cathedral and the Bishop's Palace, alongside with a few palazzi of some of the aristocratic families of the region: Aurisicchio, Ayroldi, Bisantizzi, Falghieri, Ghionda, Giovine, Jurleo, Marseglia, Moro, Palmieri, Petrarolo, Siccoda, Urselli, Zaccaria.
Outside the town, in the country's landscape there is the typical presence of the Pugliese "masserie", fortified large estate-farms, among which San Domenico, a masseria once held by the Knights of Malta.