Today, a mausoleum is any kind of aboveground, enclosed tomb. Wikipedia lists over 250 of them, and those are just the notable ones. You'll find several in the average cemetery. Well, the whole story of that word origin goes back to one person: the Persian satrap Masoulus, who fancied Hellenic architecture and kicked the bucket around 350 BCE. His grieving wife/sister (yes, one person; those were weird days) decided to build him a large Greek-style burial monument, not too unlike the Egyptian pyramids in idea but quite innovative in architecture. After suppressing a rebellion, his widow-sister finished building it, the Greeks adopted it as a word (mausolos back then) to describe such tombs, which became popular, then it went into Latin and eventually English as mausoleum. As for the origin of Masoulus's name, it's uncertain, but probably Proto-Indo-European through Proto-Iranian. Funny how Masoulus' indeed ensured he'd be remembered by history, but not in the way that was expected.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.