Superstructive

n. [ Cf. F. superstructure. ] 1. Any material structure or edifice built on something else; that which is raised on a foundation or basis; esp. (Arch.), all that part of a building above the basement. Also used figuratively. [ 1913 Webster ]

You have added to your natural endowments the superstructure of study. Dryden. [ 1913 Webster ]

2. (Railway Engin.) The sleepers, and fastenings, in distinction from the roadbed. [ 1913 Webster ]