Philadelphia’s Arch Street Friends Meeting House at 4th and Arch has this display showing how Arch Street got its name. William Penn named the streets connecting the Delaware and Schuylkill rivers after trees, and Arch Street was originally Mulberry Street. The banks of the Delaware were high and Mulberry cut through a narrow stone arch to the water’s edge, hence the common name that most settlers used.
(Race Street was originally Sassafras Street that led to races held in the countryside, Market Street was High Street, the highest street leading from the Delaware, and South Street was Cedar Street, the southernmost boundary of Philadelphia. Dock Street was the only crooked street, crossing Second and Walnut. It followed Dock Creek that emptied into the Delaware. The creek was so named in the expectation that it would become the main dock for Philadelphia that never happened. Business along these streets today sometimes take their names from the old street names.)
The diorama shows William Penn and his surveyor looking up Arch and the tiny bridge that gave it its name (no sign of the Troc yet). Click to enlarge.