Lonely Planet review
Margate's unique attraction is this mysterious subterranean grotto, discovered in 1835. It's a claustrophobic collection of rooms and passageways embedded with 4.6 million shells arranged in symbol-rich mosaics. It has inspired feverish speculation over the years but presents few answers; some think it a 2000-year-old pagan temple, others an elaborate 19th-century hoax. Either way, it's an exquisite place worth seeing.