The Guggenheim Bilbao is often considered Gehry's most famous building, positioned along the Nervión River in the old industrial center of the city. The client, director of the Solomon R. Guggenheim Foundation, Thomas Krens, encouraged Gehry to produce an innovative design which would reflect and enhance the contemporary art collection that was to be housed inside. The building received an overwhelming positive critical response, which was, perhaps, best epitomized by the architect Philip Johnson, who called it "the greatest building of our time". It is frequently named as one of the most important works of contemporary architecture in surveys such as the World Architecture Survey.
Designed using pioneering 3D modelling software, the Guggenheim Bilbao comprises a group of interconnected volumes in stone, glass and titanium-clad steel. The random arrangement of protruding shapes on the building's exterior give a very different effect when viewed from different angles, but they belie the organization within. Inside a variety of irregularly shaped gallery spaces (that can accommodate a variety of artworks, including those of a monumental scale) are arranged around an atrium, which is filled with natural light and offers picturesque views of the surrounding hills and estuary. The architect said of the building's geometry: "the randomness of the curves are designed to catch the light".
The metal cladding references the industrial past of the city, whilst also being reminiscent of the sea faring vessels that transported goods into and out of the port. Art critic Calvin Tomkins likened the whole to "a fantastic dream ship of undulating form in a cloak of titanium". As well the sails of a ship, its appearance has also been compared to a fish. Both Gehry and his critics have acknowledged a recurring fish motif throughout his work; in silvery scale-like cladding, in curving protrusions like fins, and, more explicitly, in his fish sculptures El Peix (The Fish, 1992) and Standing Glass Fish (1986). Whilst some suggest the theme is inspired by ancient symbolism, others propose it recalls aspects of Gehry's childhood: the carp kept by his grandparents or even to the traditional Jewish gefilte fish dish. Gehry himself has said: "I never intended to build fish ... In my mind, I say 'Enough with the fish.' But it has a life of its own".
The building, as well as the gallery it houses, has made Bilbao into a popular tourist destination and boosted the city's economy to such an extent that similar surges are now dubbed "the Bilbao effect". (One statistic has the number of foreign visitors to Bilbao increasing seven-fold between 1999 and 2011, with a boost of billions of euros to the local economy). Consequently, the museum has become as famous for its economic effect as its striking appearance. Some have linked the Bilbao effect to the notion of "starchitecture" (architecture of showstopping or celebrity status), but Gehry has repeatedly and violently rejected this label, stating that he is "just an architect", whose job it is to make buildings that are "technically and financially good". Since 1997 there have been other attempts, both successful and unsuccessful, to revitalize areas in this manner, for example Daniel Libeskind's expansion of the Denver Art Museum and Gehry's Walt Disney Concert Hall.