Plymouth Rock , a granite boulder on the shore at Plymouth, Massachusetts, onto which, according to tradition, the Pilgrims stepped as they landed from the Mayflower in 1620. The story was first told in 1741 by an old man whose father had been a Pilgrim. The incident did not come to public attention, however, until 1774. Upon hearing the story, Plymouth residents undertook to move the rock to a public square, but it split in two, and for many years the two sections were displayed separately. The rock, joined back together, is now under a granite canopy built in 1920 for the 300th anniversary of the landing of the Pilgrims.