 Most of these structures employ a brick and glass infill system within an exposed steel frame.When he was given the opportunity to design Crown Hall in 1950, Mies deviated from the norm and built a totally different structure which no one had seen before.Widely regarded as one of Mies van der Rohe's masterpieces, Crown Hall, completed in 1956, is one of the most architecturally significant buildings of the 20th century Modernist movement.