It looks like a town from a Christmas crèche, set on a tufaceous cliff a the charming spot in the craterous basin of Lake Bolsena, less than five kilometres away. Standing like a fortress amidst the "little mountain of nestled houses" (according to the description of a local poet) is the basilica of San Giovanni Battista, designed in the seventeenth century by Gerolamo Rainaldi (over previous buildings) and completed during the mid-eighteenth century by Andrea Selvi. On the main altar, in all its rich eighteenth-century glory, is a wooden polychrome statue of Our Lady of Suffrage (seventeenth century) that is widely venerated throughout the area. Every ten years, the statue is carried in procession through the town. At the inner door of the entrance, there is a nineteenth-century organ (Morettini). The various paintings in the church include a seventeenth-century altarpiece by Francesco Nasini (Our Lady of the Rosary and the Mysteries of the Rosary) and an altarpiece by the Reni school (Crucifix between St. Mary Magdalene and St. Francis of Assisi). The sacristy leads to a rich antiquarium located in the area under the apse: sacred paraments, chalices, reliquaries, ciboria, bulls, votive offerings, missals, candelabras, parchments and a mummified woman.

The Civic Museum is located in the former Palazzo del Podestà and it comprises two sections, Etruscan and medieval. Exhibited in the Etruscan section are several funerary furnishings from the necropolises of Vigna, Piazza and Pianezze (seventh-fourth century BC). In the medieval section, there is a reconstruction of the more recent history of Grotte di Castro and its popular traditions, with panels and illustrations. A short distance out of town along the road descending to Lake Bolsena is the Etruscan necropolis known as "Pianezze". Its tombs date to the seventh-sixth century BC. The sepulchral rooms comprise a dromos carved in tuff and a vestibule with central beams and a sloping roof. The "Red" tomb is particularly interesting.