Fortification Hill is a prominent mountain in northwestern Arizona within the Lake Mead National Recreation Area, near the southern reaches of Lake Mead and just northeast of Hoover Dam at the northwestern end of the Black Mountains. Broad and nearly mesa-like, it rises to 3,719 feet, with its highest point on the southeast end and slopes descending north and northwest toward the lake. Its flat summit was formed by Tertiary basaltic lava flows. Because it stands above Lake Mead, it is a striking regional landmark, visible across Las Vegas Bay and from the northern ends of the Eldorado and Black Mountains.