Shell Grotto at Margate - made of 4.6 million shells, 2000 square feet of mosaic and one big mystery.
In 1835, James Newlove lowered his young son Joshua into a hole in the ground that had appeared during the digging of a duck pond. Joshua emerged describing tunnels covered with shells. He had discovered the Shell Grotto; 70ft of winding underground passages leading to an oblong chamber, its walls decorated with strange symbols mosaiced in millions of shells. Nobody can explain who built this amazing place, or why.