This is for sites concerning the monuments, tombs, and other architectonic constructions prominently featuring very large (mostly shaped) stones.
Websites presenting alternative or non-orthodox views of megaliths (perhaps a proposal on esoteric meaning, or creation by advanced civilisations) will not be listed here. Submit them to Science/Social_Sciences/Archaeology/Alternative/Megaliths
Megaliths in the Channel Islands
Megaliths in Ireland, including Northern Ireland.
Megaliths in the United Kingdom.