Grotta Tanaccia is an ancient rock niche on the edge of Monte Titano, located just outside the city walls near Montale Tower.
The niche in the cliff face of Monte Titano, cave feels too grand a word for what you'll find, saw active use as a place of worship from the second Iron Age, through the Roman period and to the late-antique period. Grotta Tanaccia is therefore considered the oldest sanctuary in the Republic of San Marino.
Excavations here have discovered bronze votive offerings, anatomical terracotta offerings depicting arms and fingers, and over a hundred coins. All of these treasures can be seen in the State Museum of San Marino.