The Middlesex Canal was a 27-mile barge canal connecting the Merrimack River with the port of Boston. Construction began in 1794 and it was operational by 1802. At first it ended in Medford, and barges continued to Boston along the Mystic River. A branch canal to Charlestown was built in 1804.

This wonderful watercolor by Thomas Dahill forms the cover of “The Incredible Ditch,” published by the Medford Historical Society and co-written by Dahill and Alan and Carl Seaburg. The Royall House, with the Slave Quarters visible beyond it, stands on a rise above the intersection of the river and the branch canal into Medford (what is today Medford Square)