Plymouth, << PLIHM uhth, >> Rock, a granite boulder with the date 1620 carved on it, lies near the sea at Plymouth, Mass. According to a popular story, a party of Pilgrim explorers from the Mayflower stepped ashore on this rock when they landed at Plymouth on Dec. 21, 1620. Many historians, however, doubt that the Pilgrims actually stepped on the rock. It is more likely that the rock was near the spot where the Pilgrims landed. The rock was moved several times between 1774 and 1921. Today, it stands under a granite canopy near the water’s edge, where it serves as a memorial to the landing of the Pilgrims in 1620.