The Monastero di Santa Croce stands on a wooded headland directly above Bocca di Magra, reached by a short uphill walk from the village. The site has been religious since at least the 6th century; the present buildings — a small Romanesque church and a low cloistered convent — date in their oldest parts to the 11th century.
The terrace beside the church is the best viewpoint in Bocca di Magra, with the river curving below, the Apuan Alps to the east, and the open Ligurian Sea to the west. The monastery is still active and is run by a small community of nuns who welcome visitors during daylight hours.