Santissima Trinità, Collegiate church in Genzano di Roma, Italy.

Santissima Trinità is a neoclassical collegiate church in Genzano di Roma with a striking facade divided into three sections, where the central part rises higher and is flanked by two column orders in Tuscan and Ionic styles. Inside, it holds eleven altars and several chapels, including one dedicated to Saint Thomas of Villanova.

Construction began in 1781, the year after the opening of the Via Corriera to Naples in 1780 broke Genzano's geographic isolation and shifted the town centre down towards the plain. The church was opened for worship on 9 April 1808 and became a parish in 1820. Rather than one designer, the work is attributed to several architects of the Camporese family, chiefly Giuseppe and his elder brother Giulio.

Locals call it "Chiesa nuova" or "Duomo nuovo", contrasting it with Santa Maria della Cima, the "Duomo vecchio"; the names mark the shift of Genzano's centre from the hilltop castle toward the plain after the Via Corriera to Naples opened in 1780. The fourteen Via Crucis panels and an early 17th-century oil of the Assumption came from the older church.

The facade faces the town centre and is reached from Piazza San Sebastiano along Via Italo Belardi. Enter by the large central portal or the two side doors; the right door leads into a corridor with four small chapels. The single bell tower stands on the right side, rebuilt after the original collapsed in the early 1900s.

The fourteen Via Crucis panels and a 17th-century oil of the Assumption came from Santa Maria della Cima, the older church on the hill. The wooden pulpit between the second and third arches of the left aisle carries a gilded relief usually read as Saint Benedict handing over his monastic rule.