the 1920s, are made from thin steel reinforced concrete, and in many cases lack any ribs or additional reinforcing structures, relying wholly on the shell structure itself. Shells may be cast in place, or pre-cast off site and moved into place and assembled. The strongest form of shell is the monolithic shell, which is cast as a single unit. The most common monolithic form is the dome, but ellipsoids and cylinders (resembling concrete Quonset huts / Nissen huts) are also possible using similar construction methods. Geodesic domes may be constructed from concrete sections, or may be constructed of a lightweight foam with a layer of concrete applied over the top. The advantage of this method is that each section of the dome is small and easily handled. The layer of concrete applied to the outside bonds the dome into a semi-monolithic structure. Monolithic domes are cast in one piece out of reinforced concrete and date back to the 1960s. Advocates of these domes consider them to be cost-effective and durable structures, especially suitable for areas prone to natural disasters. They also point out the ease of maintenance of these buildings. Monolithic domes can be built as homes, office buildings, or for other purposes. Completed in 1963, the University of Illinois Assembly Hall, located in Champaign, Illinois was and is the first ever concrete-domed arena (see also the Gridshell-like Centennial Hall in Wrocław, Poland from 1913). The design of the new building, by Max Abramovitz, called for the construction of one of the world’s largest edge-supported structures. See Construction of Assembly Hall. The Seattle Kingdome was the world's first (and only) concrete-domed multi-purpose stadium. It was completed in 1976 and demolished in 2000. The Kingdome was constructed of triangular segments of reinforced concrete that were cast in place. Thick ribs provided additional support. See also Thin-shell structure Persons related Félix Candela Pier Luigi Nervi Eduardo Torroja Heinz Isler Ulrich Müther References External links Mark Ketchum's Concrete Shell page Historic Preservation of Thin-Shell Concrete Structures - Includes case studies of the Seattle Kingdome and MIT's Kresge Auditorium, both concrete dome structures. Heinz Isler in Structurae web page Heinz Isler in Princeton University Art Museum Structural system Concrete dome + Modernist architecture +