The Mayflower Drops Anchor in Plymouth Harbor, Location of Plymouth Rock, where Colonists are Said to Have First Set Foot on Land

The Mayflower dropped anchor in Plymouth Harbor on December 17 and spent three days surveying for a settlement site. They rejected several sites, including one on Clark's Island and another at the mouth of the Jones River, in favor of the site of a recently abandoned Native American settlement named Patuxet. The location was chosen largely for its defensive position; the settlement would be centered on two hills: Cole's Hill, where the village would be built, and Fort Hill, where a defensive cannon would be stationed. Also important in choosing the site, the prior Indian villagers had cleared much of the land, making agriculture relatively easy. Although there are no contemporary accounts to verify the legend, Plymouth Rock is often hailed as the point where the colonists first set foot on their new homeland.

The area where the colonists settled had been identified as "New Plymouth" in maps by John Smith published in 1614. The colonists elected to retain the name for their own settlement—after their final point of departure from England: Plymouth, Devon.

http://en.wikipedia.org/wiki/Plymouth_Colony