San Giovanni Battista, Romanesque collegiate church in Chianciano Terme, Italy.

San Giovanni Battista is a collegiate church built in 1229 near Porta San Giovanni, showing transitional features between Romanesque and Gothic architecture, especially on its stone gabled facade. The portal is strongly splayed with bundled half-columns and capitals with plant motifs; two central twisted half-columns support an arch with the same decorative motif. A 14th-century marble statue of St. John the Baptist stands on the tympanum. Inside, a single nave ends with a dome, flanked by two side chapels.

The church was built during the medieval period and bears architectural features from different construction phases that document its long history. Its designation as Italian national heritage recognizes its importance as a testimony to the artistic and religious development of the region.

The church is dedicated to St. John the Baptist, whose marble statue from the 14th century stands on the facade tympanum. In the left Baptistery Chapel are the circular travertine baptismal font from the ancient baptistery and Bartolo di Fredi's 14th-century fresco known as the Madonna del Castagnolo. The right chapel, dedicated to the Blessed Sacrament, holds an 18th-century gilded-wood reliquary of the Holy Cross and Giuseppe Paleari's wooden Dead Christ of 1783.

The church stands inside the old town walls beside Porta San Giovanni, the main gateway, so it is reached on foot through the historic centre. The organ loft is on the counterfacade, above the entrance, and the two side chapels open off the single nave, the Baptistery Chapel on the left and the Blessed Sacrament Chapel on the right.

The church stands on the site of an Etruscan hexagonal temple later rededicated to the god Janus in Roman times. During restoration of the presbytery in 1809, two brick floors laid in herringbone pattern were found, belonging to the building's earliest phases.