Highlights of the Guggenheim Museum Bilbao

It took four years to build the museum located on the bank of the Nervion River. Clad in glass, titanium and limestone, the Deconstructivist structure designed by architect Frank O. Gehry appears to defy gravity. It has been hailed as the "greatest building of our time" by one of his colleagues, architect Philip Johnson.

It's hard to believe that such a building could emerge from a draft that looks like mere scribbles. When designing a building, Gehry says that he prepares several sketches in this style — usually spending 15 seconds on each one. He keeps drawing until he feels he's found the right design.

The central atrium, 50 meters high, is flooded with light and offers tons of playful details for the eyes: towers, gallery, corners, ramps, windows and lights. Still, the delightful architecture of the building's interior doesn't steal the show from the art.

Commissioned by the museum and of the permanent exhibition, Richard Serra's sculpture series "A Matter Of Time" is truly monumental. Frank Gehry even had to design a special large hall for the massive pieces made of steel. The "Fish" gallery is 142 meters long and 27 meters wide and comprises different works by Serra, his "Spiral" and "Ellipse" variations, as well as his "Snake" sculpture.

"Maman" is the name of the famous installation by French sculptor Louise Bourgeois on the museum's forecourt. It is made of bronze, almost 10 meters high and weighs over eight tons. The name "Mommy" comes from the fact that the spider carries 26 marble eggs in her sack. "Maman" has many sisters around the world, for example in Tokyo, Saint Petersburg, Ottawa and Seoul.

"Puppy" is the name of the cute, 12-meter-tall flower dog created by the American art superstar Jeff Koons. The artist planted 17,000 marigolds, petunias, begonias and other flowers on the puppy-like statue, and although he is supposed to guard the museum, he is always keen to pose for a photo. In 2015, the museum held a major retrospective of the popular artist.

American artist Mark Rothko was one of the main figures of abstract expressionism. He let the colors on his paintings speak for themselves to achieve a direct communication between the picture and the viewer. The surfaces, shadows, patterns and brush strokes he created were never random. "Untitled" (1952), above, is one of the museum's highlights.

In 2004, the Guggenheim Museum in Bilbao dedicated a large exhibition to pop art pioneer James Rosenquist. The artist, who died in April 2017, is renowned for his huge paintings in which he'd compose seemingly random motifs in oversaturated colors. The artwork in the picture, the "Star Thief," was a loan from the Museum Ludwig in Cologne.

In 2012, the museum featured the largest exhibition ever dedicated to the early work of the Swedish pop artist Claes Oldenburg. His style is characterized by oversized sculptures of everyday objects such as lipsticks, clothespins, cakes, burgers or fries with ketchup made of cheap materials. The show then traveled to Vienna, Cologne and New York.

To celebrate the 20th anniversary of the institution, the Guggenheim Museum was lit up by an impressive 3D light installation that took place over four evenings in October. The performance was created by the British video designers "59 Productions" and took viewers on a journey throughout the history of the museum and art.