The Massachusetts Institute of Technology (MIT) Great Dome is a 100-foot (30.5 m) diameter concrete and limestone dome. It sits on top of Building 10 in the heart of the MIT campus. Completed in 1916, the whole building complex is an early example of steel reinforced, concrete construction. Building the dome required a grid-like scaffolding framework to create the dome shape which was then poured with concrete and covered with limestone blocks imported from Indiana.
Under the Great Dome is a 75-foot (22.9 m) diameter rotunda capped with an internal 75-foot (22.9 m) diameter decorative dome. A 27-foot (8.2 m) oculus — which was recently restored after being covered for over 70 years — allows natural light into the Barker Engineering Library reading room below.