The "Radiance" class ships were constructed at Meyer Werft, Papenburg, Germany. Unlike the preceding "Voyager" class, these ships are built to the Panamax form factor, allowing them to pass through the Panama Canal. The "Freedom"-class ships are lengthened versions of the second-generation "Voyager"-class ship, and contain a Royal Promenade mall running much of the length of the ship, an ice skating rink, basketball court, several pools, a mini-golf course, and a rock wall. New features on the "Freedom" class include the FlowRider surfing simulator, the H2O Zone kids water play area, a boxing ring, and hot tubs cantilevered over the side of the ship. At 154,407 gross tons, the "Freedom"-class ships were the largest ships in the world from 2006, until the debut of the Oasis class in 2009. The "Oasis"-class ships are the largest passenger ships ever built, having surpassed "Freedom"-class ships. They can accommodate up to 5,400 passengers at double occupancy and they have a maximum capacity of 6,296 passengers. Furthermore, the ships have a gross tonnage of at least 225,282 tons, and cost the line around US$1.4 billion each. The first two ships in the class, "Oasis of the Seas" and "Allure of the Seas", were delivered in 2009 and 2010 by STX Europe Turku Shipyard, Finland. The third and fourth ships in the class, "Harmony of the Seas" and "Symphony of the Seas" were built at Chantiers de l'Atlantique in Saint-Nazaire, France. Royal Caribbean International, in conjunction with USA Today, sponsored a contest to name the first two vessels. On February 18, 2019 Royal Caribbean announced the order of a 6th Oasis class vessel from Chantiers de l'Atlantique for delivery in 2023 with a double occupancy of 5,714 and gross tonnage of 231,000. The "Quantum"-class of ships debuted as the second largest class of cruise ships in the world. The "Quantum"-class ships were the first ships built for Royal Caribbean by Meyer Werft since the "Radiance" class and share many features with those ships, including indoor pools with retractable roofs, vast expanses of glass, outdoor seating in the "Windjammer" buffet, and self-leveling pool tables.