Necropolis

A necropolis (plural: necropolises or necropoleis) is a large cemetery or burial place (from Greek nekropolis "city of the dead"). Apart from the occasional application of the word to modern cemeteries outside large towns, the term is chiefly used of burial grounds, often an abandoned city or town, near the sites of the centers of ancient civilizations.

Catacombs

Catacombs are ancient, human-made underground passageways or final resting place of refuges or subterranean cemeteries composed thereof.  Many are under cities and have served as a refuge for safety during wars or as a meeting place for cults during historic times.

Apse

In architecture, the apse is a semicircular recess covered with a hemispherical vault or semi-dome.

Dervish

A Dervish or Darvesh  is someone treading a Sufi Muslim ascetic path or "Tariqah", known for their extreme poverty and austerity, similar to mendicant friars in Christianity or Hindu/Buddhist/Jain sadhus.