Is there a single word for a cemetery full of tombs that are above ground?

Solution 1:

Necropolis may be an option.

Wiktionary says:

A large cemetery, especially one of elaborate construction in an ancient city. [...] From Ancient Greek νεκρόπολις (nekrópolis, “city of the dead”), from νεκρός (nekrós, “dead”) + πόλις (pólis, “city”).

Although not limited to the type of cemetery described by the OP, some authors use the term. Necropolis also used for cemeteries where bodies buried but with significant structures/monuments above ground, like the Glasgow Necropolis. The ancient Egyptian pyramids are also referred to using the term.

Quoting Mysteriousheartland.com

Inside New Orleans’ Necropolis.
[...] Opened in New Orleans in 1789, Saint Louis Cemetery No. 1 is one of the most famous cemeteries in the United States, if not the world.[...] a few blocks from the French Quarter, its strange residents and aged, crumbling aboveground vaults make this necropolis a popular tourist destination.

Wikipedia states:

A necropolis is a large ancient cemetery with elaborate tomb monuments. Ancient Greek νεκρόπολις nekropolis, literally meaning "city of the dead". The term implies a separate burial site at a distance from a city as opposed to tombs within cities, which were common in various places and periods of history. They are different from grave fields, which did not have remains above the ground. While the word is most commonly used for ancient sites, it has also been used for some modern cemeteries such as the Glasgow Necropolis.