Santissima Trinità, Franciscan convent in Santa Fiora, Italy.

Santissima Trinità is a Franciscan convent on Monte Calvo within a forest setting, featuring a baroque church with three ornate altars and detailed architectural elements. The entire complex integrates religious architecture with its surrounding natural landscape.

The first church, Santissima Trinità nella Selva di Monte Calvo, was built in the 11th century with a small hermitage beside it. Count Guido II Sforza had it rebuilt and enlarged between 1488 and 1489, incorporating the earlier church; he spent his last years there and was buried in the convent in 1508. The present church was rebuilt in 1762, demolishing the previous one.

The name comes from the church of the Santissima Trinità, first built in the 11th century as a small church in the Selva di Monte Calvo. A wooden case in the room before the sacristy holds the upper part of the skull of the "serpente", probably a crocodile escaped from the Santa Fiora fishpond, killed by Count Guido II near the spot still called Fosso Serpentaio.

The convent sits on a forested mountain, so visitors should expect some walking and natural surroundings. Spring and summer are best for visiting when paths are most accessible and weather is favorable.

Near the convent stands the Fonte del Papa, named for Pope Pius II, who according to legend drank from it while gravely ill and was miraculously cured. The adjoining chapel of Santo Stefano is managed by the Diocese of Pitigliano-Sovana-Orbetello.