• Dolmens in Korea, some of which are believed to be tombs. Also menhirs, pyramids, petroglyphs.
• Ireland: Light, Body and Soul, A Photographic Essay of Spiritual Places in Ireland. Contains some buildings, standing stones, a dolmen, and some celtic-looking stone art.
• jbmeier's list of links to sites describing megaliths
• Stones of Wonder: Prehistoric Observatories in Scotland
• There is more between heaven and earth (click "megalithic". !@#$ frames.)
• The Center for archaeoastronomy