The Guggenheim Museum Bilbao was complete in October 1977 and took Gehry about 4 years to build.  The museum was created a curve on the Nervion and helped revitalize the culture and leisure around the river banks of the city.  Gehry used some advanced technology like CATIA to help with the mathematical designs of the building. CATIA was built as an aerospace technology but was transformed to help with the construction.  Gehry used titanium as the outside metal sheet of the museum because of it behavior in different elements.  The 33,000 extremely thin titanium sheets provides a rough and organic effect, adding to the material’s color changes depending on the weather and light conditions.  The museum was also built with limestone and glass to help the building come together.  The building has become and iconic building of not only Spain and and the world.