The Guggenheim Museum Bilbao is a museum of modern and contemporary art designed by Canadian-American architect Frank Gehry. Opened in 1997, it is hailed as one of the most important structures of the 20th century. The building is famous for its organic, sweeping curves, which were made possible through the use of CATIA, a sophisticated computer-aided design software originally used in the aerospace industry. The exterior is clad in 33,000 extremely thin titanium sheets, chosen for the way they catch and reflect the light of the Nervión River. The 'Bilbao Effect' refers to how the museum's success completely transformed the city's economy from a struggling industrial port into a global tourism hub. Notable features include the massive atrium, nicknamed 'The Flower,' and outdoor sculptures like Jeff Koons' 'Puppy.'