It's one of the most important sites in the history of the United States—but we still don't know where, exactly, it was. That's why University of Massachusetts archaeologists are digging for signs of the original Plymouth colony, the Boston Globe reports. The borders of today's Plymouth don't quite match those of the Pilgrims' settlement, which was marked by palisades built in 1622 around a hilltop fort. The town "is well situated upon a high hill close unto the seaside," wrote a visitor in 1623, describing a plantation of 20 houses, as Smithsonian notes.
The area hadn't been dug up before because of the potential for running into unmarked graves. But ground-penetrating radar allowed researchers to ensure they wouldn't hit any. They're digging around the sites of 19th-century buildings that may have been built over 17th-century houses. The wood of the palisades will have rotted away, but stains left in the soil could show where they once were, says an archaeologist. (Last year saw the auction of a Plymouth book of Bible verses—making it the world's most expensive book.)