Ptolus lies between the Spire and the sea. The highest portion of the city, the Nobles’ Quarter, is built on the base of the Spire. From there, the level of the city drops down a sharp cliff to Oldtown, and then down again into Midtown. The final cliffs at the edge of Ptolus drop into the bay, with the only area of dry land at the bottom of those cliffs occupied by the city’s docks. Wellworn paths connect the various elevations and help make Ptolus very defensible (although the city has never been attacked).

The King’s River flows through the city, spilling into an eroded chasm in the northwest corner and flowing down to the Bay of Ptolus near the docks. The bottom of the chasm, called the King’s River Gorge, is eighty feet below the level of the ground on its north side, but more than two hundred feet below on its south side. The south side still holds the old city walls and fortifications. A bridge built upon two massive pillars, themselves erected atop natural rock columns, stretches across the King’s River Gorge at a steep angle, leading into the area of the city known as Oldtown. Another bridge stretches across the chasm to join Oldtown with the Rivergate District. Although Oldtown is higher, the difference in elevation between these two districts is not steep, so the slope of this bridge seems far less noticeable than that of the other.