Frank Lloyd Wright (1867-1959) was a prominent American architect, writer and teacher. His design philosophy was based on the idea that structures should harmonize with their environment. This approach was best exemplified by Fallingwater (1935) and his many Prairie Homes. However, he also designed numerous lesser known structures. One of which stands in Wauwatosa, a city in Milwaukee County, WI, USA, only a few miles from my hometown. The Annunciation Greek Orthodox Church was designed and proposed in 1956, near the end of Wright’s life. In fact, it was not constructed until 1959, after his death.
For the design of this thin shell dome, Wright was inspired by the Hagia Sophia (Istanbul, Turkey). The reinforced concrete dome is unique. First, it is extremely thin for its size. The dome has a 16.2m radius (the Hagia Sophia’s radius is 15.5m) and a height of about 4m (Hagia Sophia’s height is 15m). However, the average thickness of the concrete shell is only 9cm whereas in the masonry Hagia Sophia dome the average thickness is 76cm. Second, the dome rests along its perimeter on greased steel ball bearings. Milwaukee has a wide range of seasonal temperatures and the ball bearings allow the dome to expand and contract about 2 cm of movement due to temperature variations. Finally, the dome is detailed along its perimeter with a series of glass orbs which let light in and give the illusion that the dome is levitating above the building. This resembles the design of the Hagia Sophia, interior pictured below, which has windows allowing streams of light to pass around the perimeter of its dome as well.