Once, long ago, about 52 barrows and dolmens lay on Lyø. Today, only 5 of them remain intact. The dolmens were used as burial chambers for the leading figures on Lyø society as well as their families. The largest and bestpreserved, The Bell Stone, a dolmen chamber from between 3500-3100 BC, lies on a 20 m high hill on the west side of the island. From here there is a fine view of the Little Belt, Horneland and Lyø Trille.
Around 1920, a grove was planted at this spot, which the islanders used as a meeting place in connection with Constitution meetings. The Bell Stone has got its name since by striking various places on the cover stone it is possible to produce a bellike sound, and, it is said, to have a wish granted.