[custom_adv] From the stately rows of palm trees on its 52-acre grounds to the grand double staircase to the glittering ballroom chandeliers, it is easy to see why the six-year-old Ritz-Carlton in Riyadh, the capital of Saudi Arabia, has played host to billionaires, heads of state and members of the Saudi royal family. [custom_adv] Which is why it is all the more jarring that former government ministers, prominent businessmen and members of the royal family — the House of Saud — are being held captive in the five-star hotel, which was swiftly converted over the weekend into what is almost certainly the world’s most luxurious prison. [custom_adv] In a shaky video that appears from its metadata to have been shot early Monday morning in the hotel’s Ballroom B, people can be seen lying on mats covered with brightly colored blankets in floral motifs while guards in dark uniforms are visible in the background. In a corner stands a rifle, which appears to be an American standard military-issue M4, its civilian variant or a copycat. [custom_adv] The ballroom appeared to be a makeshift barracks for guards, while the V.I.P. detainees were being held in some of the hotel’s 492 guest rooms and suites. A search of the hotel’s reservation page on Tuesday showed that it was “not available for check-in” until December 16. [custom_adv] The country’s attorney general, Sheikh Saud al-Mujeb, said on Monday that detainees had been subjected to detailed interrogations. He said the investigations were being conducted in secret to protect the integrity of the legal procedures and to ensure that the detainees’ high social status would not exempt them from justice. [custom_adv] Ironically they are huddled on the floor of one of the grand function rooms which last month played host to the Future Investment Conference, a gathering of world business leaders which Prince Mohammed used to highlight his commitment to turning Saudi Arabia to 'moderate and which some of those arrested attended. [custom_adv] Ballroom B, where the video footage appears to have been taken, is just shy of 20,000 square feet, and can be used as a banquet room seating 1,400 people or a reception accommodating 2,000 people. [custom_adv] Those arrested have been locked in the five star hotel as the sweeping anti-corruption probe ordered by Saudi King Salman's son, Prince Mohammed bin Salman, continues. [custom_adv] As with most public spaces in the kingdom, the hotel does not permit shorts, skirts or tank tops. It asks that guests dress modestly, either in local attire, smart casual or formal wear. [custom_adv] The arrests that began late Saturday included Prince Miteb bin Abdullah, who for the past four years had led the National Guard, and Prince Adel Fakeih, who was minister of economy since April. [custom_adv] The royal and non-royal prisoners are reportedly confined to the five-star Ritz-Carlton Riyadh in the nation's capital.