Aia (/ˈaɪ.ə/; Basque: [ai.a]) is a small village situated on the slopes of Mount Pagoeta in the Basque province of Gipuzkoa, Spain. It is located 30 km to the west of Donostia-San Sebastián and about 10 km inland from the coastal town of Zarautz. Aia is set amongst hills and forests, and surrounded by mountains. The town still retains its ancient character, with the large Church of San Esteban building as an impressive centrepiece.