“Late 19th century: This atmospheric shot of the passage tomb entrance shows a man emerging from its dark interior. It was taken by R. J. Welch sometime in the late 19th century and it shows an overgrown and partially disturbed mound. Although the roofbox, through which the winter solstice sun rays should pass, is completely blocked, its decorated stone lintel can still be partially discerned c. 1 m above the entrance passageway” (Irish Archaeology).
Before excavation and restoration (think “concrete wall”) began in the 1960s, the famous Irish Neolithic temple of New Grange (older than the Pyramids!) looked quite different. The Irish Archaeology site offers sketches and photos from the 18th century forward.