More to explore:
Cave Of Melody, Scotland
Cave of Melody, Scotland Fingals Cave
Fingal's Cave on the island of Staffa in Scotland
Maze at Traquair House, Scotland | by © Alex
Crystal Cave, Iceland
Madrid High Trestle Bridge: The 13-story high bridge over the Des Moines river is a half mile long and was built on concrete piers that previously held a railroad bridge. 41 steel frames form a twisting tunnel.
Cave of Melody, Scotland - Hmmm... Melody Pond? I do see a River of some sort. en.m.wikipedia.or...
Fingal's Cave, Scotland
Fingal's Cave, UK. Columnar basalt.