Shell Grotto - Margate - Kent, UK

The Shell Grotto is an ornate subterranean passageway shell grotto in Margate, Kent, England. Almost all the surface area of the walls and roof is covered in mosaics created entirely of seashells, totaling about 2,000 square feet (190 m2) of mosaic, or 4.6 million shells.
The purpose of the structure is unknown and various hypotheses date its construction to any time in the past 3,000 years. Hypotheses include: it was an 18th or 19th-century rich man’s folly; it was a prehistoric astronomical calendar; it was a meeting place for sea witchcraft; and it is connected with the Knights Templar or Freemasonry.

The mysterious shell grotto of Margate – Part 1 & 2:
https://www.ancient-origins.net/ancient-places-europe-unexplained-phenomena-opinion-guest-authors/mysterious-shell-grotto-margate

https://www.ancient-origins.net/unexplained-phenomena-ancient-places-europe-opinion-guest-authors/mysterious-shell-grotto-margate-0