other side of the floor. The floor itself is covered with the largest continuous mosaic in the US, which morphs its way up columns. In one area is a tunnel known as the "Underground Whaleway" which runs beneath the floor and into the "Original Caves." One of the museum's most popular attractions, the Enchanted Caves and Shoe Shafts run through the center of the museum all the way to the 10th floor. Opened in 2003, the Caves are an elaborate system of tunnels hand-sculpted by Bob Cassilly and his crew. Since 2007, the Caves have also contained a 1924 Wurlitzer Pipe Organ from the Rivoli Theater in New York City. The Shoe Shafts were developed from structures built for the International Shoe distribution operation. To get the shoes from various floors to the loading dock, staff would place the shoes on spiral shafts. The Shafts opened in 2003 with one three-story spiral slide. Five years later, the museum added a ten-story slide that starts at the roof and leads down to the Caves' entrance. There is also a five-story slide and additional ten-story slide. The Mezzanine The Mezzanine contains the museum's food court. 2nd floor The Vault Room, an 1870s vault withdrawn from the First National Bank of St. Louis, contains two 3,000-pound vault doors and a hall of mirrors. The room also has a marble bar and about 1,000 safety deposit boxes. In the middle of the room is the "hamster wheel", a piece of machinery donated by McDonnell Douglas, which used it to make fuselages for small airplanes. Off to the side of the Vault Room and leading to the Enchanted Caves is St. George's Chamber, which holds vintage opera posters and a statue of St. George from the former Saint George's Catholic Church in Chicago. Also on this floor is The Shoelace Factory, featuring shoelace machines from the 1890s, where visitors can order custom-made laces. The World Aquarium was an animal exhibition and rehabilitation center on the second floor. It housed a variety of animals such as sharks, rays, sea turtles, parrots, tortoises, terrapins, otters, snakes, alligators and sloths as well as freshwater and saltwater fish. The World Aquarium portion of the City Museum closed on September 7, 2015, and is now located in Laclede's Landing, St. Louis. 3rd floor The 3rd Floor is home to a number of attractions. In one area is Skateless Park, which