For fun, I thought it might be interesting to include an informal top missing sites that remain undiscovered and may even be mythical. When I say "mythical" I do not mean El Dorado or Atlantis, instead sites that have well-documented evidence of
likely existence and at least sustained efforts of discovery. Considering tombs/tumuli, there have been significant efforts made to discover these sites below. There is also a myriad of lost cities that are believed to have existed.
Tomb of Alexander the GreatTomb of Antony and CleopatraTomb of AchillesTomb of Genghis Khan