Although it has lost its ancient medieval appearance and taken on a more contemporary look, there is no shortage of interesting sights in Bientina. In the main square stands the Chiesa di Santa Maria Assunta (Church of Santa Maria Assunta), where the remains of St. Valentine, the town's patron saint, are kept; the simplicity of the exterior is counterbalanced by the rich decorations of the interior, with stuccos and paintings. Attached to the church is an esteemed Museo d’Arte Sacra (Museum of Sacred Art), with a collection of religious objects and fine furnishings from the 16th-17th centuries.
Not far away, in a small square, stands the Mastio (Dungeon), once the town's upper part of the fort. Damaged during World War II and now restored, it houses the Biblioteca Comunale and the Archivio Storico (Municipal Library and Historical Archives) inside.
The former Oratorio of San Girolamo (Oratory of San Girolamo), an ancient 17th-century church now deconsecrated, houses the Museum of Ancient History of the Bientina area mentioned above with artifacts from the Proto-Etruscan and Etruscan-Roman ages found in the area, including those from the settlement once submerged by the lake.