Milwaukee’s skyline benefits from these striking structures that house three extraordinary botanical gardens. The original Mitchell Park conservatory, built in 1898, provided Milwaukeeans with indoor gardens until the building was razed for safety concerns in 1955. Grieb’s three beehive-shaped domes continued Milwaukee’s tradition of a glass-walled horticultural conservatory in Mitchell Park. Their beehive shapes (not geodesic domes) are framed by a web of triangular and diamond-shaped, steel-reinforced concrete sections welded together and covered with an aluminum and wire-reinforced plate glass skin. Each 140-foot-diameter dome is 85 feet in height. The domes illustrate the fascination with innovative structural systems and space-age modern design characteristic of the 1950s and 1960s. The Tropical Dome presents the lush vegetation and warm, humid climate of a tropical rain forest, with twenty species of birds and also lizards and toads to control insect populations. The Desert Dome supports desert and arid-land plants, and the Floral Show Dome has changing floral displays with seasonal, historical, ethnic, and fantasy themes.