Attendees at the Surveyors Rendezvous in Philadelphia continued to celebrate the 250th anniversary of the start of the Mason-Dixon survey on Friday.

James Shomper of the Surveyors Historical Society led a ceremony that dedicated an official Pennsylvania state historical marker designating the southernmost point of Philadelphia.

Near the spot where Charles Mason and Jeremiah Dixon determined was the starting point for their famous survey, Shomper and several others, including Todd Babcock of the Mason-Dixon Line Preservation Partnership, gave brief remarks highlighting the historical significance. Representatives from the South Street Headhouse District, Pennsylvania Historical and Museum Commission and Penn State-Abington also were present.

The marker was dedicated at the intersection of Front and South Streets in Philadelphia, though the exact location is believed to be in the middle of Interstate 95. There, in 1763, Mason and Dixon determined it to be the starting point of their survey, which was completed five years later.

The Surveyors Rendezvous marked the spot of Mason and Dixon’s Astronomical Observatory in Chester County, Pa., on Thursday. On Saturday, attendees will celebrate Mason by dedicating a stone at his burial site near Independence Hall.