Dug into Mount Errone (also known as the Idris rock), the rock church of Chiesa di Santa Maria de Idris has an unprepossessing façade but the narrow corridor communicating with the recessed church of San Giovanni in Monterrone is richly decorated with frescoes dating from the 12th to the 17th centuries. San Giovanni in Monterrone was originally used as a baptistery, later as a crypt, and until a few years ago contained human bones clothed in rotting rags.