went into insolvency and in June 2003, the facilities were sold off and the airship hangar was converted to a 'tropical paradise'-themed indoor holiday resort called Tropical Islands, which opened in 2004. An alternative to the fixed hangar is a portable shelter that can be used for aircraft storage and maintenance. Portable fabric structures can be built up to wide, high and any length. They are able to accommodate several aircraft and can be increased in size and even relocated when necessary. Structures and sizes Hangars need special structures to be built. The width of the doors have to be large; this includes the aircraft entrance. The bigger the aircraft to be introduced, the more complex a structure is needed. According to the span of the hangar, sizes can be classified thus: XXL hangars are built for the largest aircraft in the world like the Airbus A380, Boeing 747 and the Antonov 225, which are the most complex to erect. Regulation Hangars are usually regulated by the building codes in the countries and jurisdictions and airports where they reside. In August 2014, the American FAA proposed legislation of how a hangar can be used on airfields that receive government funding. The definition of allowed activities included final assembly of aircraft. Airship hangars Airship hangars or airship sheds are generally larger than conventional aircraft hangars, particularly in height. Most early airships used hydrogen gas to provide them with sufficient buoyancy for flight, so their hangars had to provide protection from stray sparks to keep the gas from exploding. Hangars that held several airships were at risk from chain-reaction explosions. For this reason, most hangars for hydrogen-based airships were built to house only one or two such craft. During the "Golden Age" of airship travel from 1900, mooring masts and sheds were constructed to build and house airships. The British government built a shed in Karachi for the R101, the Brazilian government built one in Rio de Janeiro, the for the German Zeppelins, and the U.S. government constructed Moffett Field, Mountain View, California and Lakehurst Naval Air Station, Lakehurst, New Jersey. Hangars aboard ships Many warships carry aircraft and will often have hangars for storage and maintenance. Such hangars may be situated adjacent to the flight deck on cruisers, destroyers and frigates or underneath the flight deck with elevators to lift the aircraft on aircraft carriers and amphibious assault ships. On some