The World Fair of 1967 was a fair old time ago but one extreme example of recycling old buildings is the Montreal Biosphere which is now the home of an environmental museum. The original acrylic shells that enclosed the dome are now gone - the steel remains however. At the time of the World Fair the building housed the longest ever escalator (thirty seven meters in length). Unfortunately a 1976 fire destroyed the acrylic shells but the building was bought by Environment Canada in 1980 and it is now an interactive museum. One of the highlights of a visit to Montreal, the museum is devoted to showing people about how the Great Lakes ecosystem can be developed in a sustainable way - this is done through a variety of exhibitions and interactive pieces.