The Guggenheim Museum in Bilbao has been called “the world’s largest toy” and the “Miracle in Bilbao.” Since its opening in 1997, it has inspired a plethora of critiques, articles, awards, artists, and visitors. Here are a dozen facts about one of the most popular art museums in Spain.

1. THE MUSEUM WAS DESIGNED BY FRANK GEHRY.

Gehry, a Canadian-born, Los Angeles-based architect, has designed some of the most iconic structures in the United States. His firm, Frank O. Gehry & Associates (now Gehry Partners), was selected by Thomas Krens, the director of the Solomon R. Guggenheim Foundation, to design the museum in 1991, beating out proposals by Austrian firm Coop Himmelblau and Japanese architect Arata Isozaki.

2. IT'S BEEN CALLED THE MOST IMPORTANT PIECE OF ARCHITECTURE SINCE 1980.

In 2005, Vanity Fair surveyed 52 experts to determine the definitive construction project of the latter half of the 20th century. The unanimous results, with 28 members of the survey (including 11 Pritzker Prize-winners and the deans of eight architectural schools) casting their votes in his favor, pointed to Gehry’s work in Bilbao as the most influential. He also received votes for the Walt Disney Concert Hall in Los Angeles, the Millennium Park bandshell in Chicago, and his private residence in Santa Monica, California.

Other vote-getters included Renzo Piano for the Menil Collection in Houston, Texas, and Peter Zumthor’s Therme Vals (Thermal Baths) Hotel and Spa in Graubünden, Switzerland.

3. THE BUILDING SITE WAS ONCE A THRIVING PORT AREA.

Bilbao, a city of 350,000 in the Basque Country of northern Spain, is located on the Nervión River and lies 7 miles inland from the Bay of Biscay, which has made it a hub of shipping activity for centuries. But the economic tumult of the mid-20th century left much of the area derelict until the region underwent a period of urban transformation that culminated with the opening of the Bilbao in 1997.

4. THE BASQUE GOVERNMENT FUNDED ITS CONSTRUCTION.

In 1991, following designs for a new airport and subway system, the Guggenheim’s Krens met with Basque government officials and agreed to build a new Guggenheim museum in Bilbao. The two sides signed a 75-year agreement, in which the government planned to pay $100 million for the museum’s construction, $50 million for an acquisitions fund, a one-time $20 million fee for the Guggenheim Foundation, and $12 million to subsidize the museum’s annual budget. Krens and the Guggenheim were responsible for managing the museum, bringing in collections and pieces of art, and creating shows.

5. THE MUSEUM WAS INAUGURATED BY A KING.

Juan Carlos I sat as Spain’s monarch from 1975 until his abdication in 2014. On October 17, 1997, Juan Carlos and Queen Sophia attended a gala for the museum’s opening, where the King intoned, “The Guggenheim Museum is inaugurated!”

6. BILBAO IS ONE OF THREE PERMANENT MUSEUMS RUN BY THE GUGGENHEIM FOUNDATION.

During his lifetime, philanthropist and mining scion Solomon Guggenheim amassed a large art collection and created the foundation that bears his name in 1937. Artist Hilla Rebay served as the foundation’s curator and was the director of the Museum of Non-Objective Painting before the opening of the permanent Solomon R. Guggenheim Museum in New York City in 1959, 10 years after Guggenheim's death. The Peggy Guggenheim Collection, a small museum first opened by Solomon’s niece, debuted in Venice, Italy, in 1951 at the Palazzo Venier dei Leoni. A permanent space in the Cultural District of Saadiyat Island is set to open in Abu Dhabi in 2017, while the Deutsche Guggenheim operated in Berlin from 1997 to 2013.

7. IT WAS THE LARGEST OF THE GUGGENHEIM MUSEUMS WHEN IT DEBUTED.

With 120,000 square feet of exhibition space and 260,000 square feet in total, Bilbao has the biggest area designated for art among all the Guggenheim projects. When it opens next year, the Abu Dhabi site will surpass Bilbao at 450,000 total square feet.

8. THE FIRST EXHIBITION FEATURED 300 PIECES.

Many of the pieces from the opening of the museum came from the Guggenheims' own collection in an exhibition called “The Guggenheim Museums and the Art of This Century.” The featured artists included Willem de Kooning, Mark Rothko, Clyfford Still, Francesco Clemente, Anselm Kiefer, and Jenny Holzer, as well as Spanish artists Antoni Tapies and Eduardo Chillida.

9. TWENTY GALLERIES ARE SPREAD OVER THREE FLOORS.

The gallery rooms are constructed with various shapes to change perspective for viewers, who can view modern and postmodern art from the mid-20th century through the present day. Current exhibitions include The Cloud of Unknowing by Ho Tzu Nyen (until April 24) and Andy Warhol’s Shadows.

10. THE ARCELOR GALLERY HOUSES THE MUSEUM’S LARGEST PIECE

Sculptor Richard Serra first displayed "Snake" in the 430-foot long “fish” gallery when the Bilbao opened in 1997. His sculpture ensemble titled "The Matter of Time" was acquired in 2005, and the massive steel pieces (some of which stand 14 feet high and weigh 22 tons) reside in the same gallery, which was renamed for the manufacturer that supplied the two-inch thick steel.

11. THE ‘BILBAO EFFECT’ PUMPED MILLIONS INTO THE ECONOMY.

It was called “the greatest building of our time” by architect Philip Johnson, and aside from its cultural and aesthetic impact, the Guggenheim Bilbao seemed to put the city itself on the world map. Upwards of 100,000 people visited the museum per month; hotels, restaurants, and public spaces were modernized; and the city generated about $100 million in taxes in the museum’s first three years of operation. Today, about a million people visit the museum per year.

12. AN EMBEZZLEMENT SCANDAL EMBROILED THE MUSEUM.

In 2008, Roberto Cearsolo Barrenetxea, the financial director of the Guggenheim Bilbao, was fired for financial and accounting irregularities to the tune of $775,000. He was sentenced to 32 months in prison in 2009 after he was found guilty of embezzlement and falsifying documents. According to The New York Times, Barrenetxea forged checks and bank transfers for seven years in order to swipe small amounts of money from a pair of museum funds, but finally confessed, “I could no longer live with this situation” after the impropriety was discovered.