At the foot of the Puig de Sant Marti mountain is the cave of the same name. In it there are 2 chapels in the Gothic style. They were used by the first Christians, where their cult was still forbidden. 1. Sant Jordi (1632) and 2. Sant Marti. The cave was closed in 1827 due to poor condition, restored in 1886 and open to the public, meanwhile it is in danger of collapsing and may no longer be entered... actually ;) I went down anyway, over the fence.
The second-century cave church of Sant Marti, one of the earliest testimonies of Christian communities in Mallorca, is closed today due to the danger of collapse and is open to visitors only on high public holidays.