40 residences will make up the 26-story development called "500 Walnut;" 14 of those will be full-floor units.
Two penthouses will feature 8,400 square feet of customizable space and private interior elevators.
The fitness center will include a yoga room, massage room and outdoor terrace overlooking Independence Mall.
Construction is set for spring 2015.
500 Walnut is set to open in 2017.
