“It is generally agreed upon that the world’s oldest playable pipe organ is located in the Basilica of Valèrein Sion, Switzerland. Built around 1435, most of the case is original, but only 12 pipes are original, as the rest have been replaced during restorations.
"The largest pipe organ ever built, based on number of pipes, is the Boardwalk Hall Auditorium Organ in Atlantic City, New Jersey. It has 449 ranks, 337 registers, and 33,114 pipes and weighing approximately 150 tons.The organ is no longer operational because of prolonged decline and damage during the renovation of the Boardwalk Hall. A workman found the cable linking the console to the pipes in his way and cut the cable, causing extensive damage that rendered the organ mostly inoperable. A portion of the organ (the Right Stage chamber) has functioned from 1998 to 2000 and a recording was made during that time. Currently, the Kimball Ballroom and the Right Stage chamber of the Main Auditorium organ are being restored to playing order again.”
"It contains the world’s largest Diaphone, the 64′ Diaphone-Dulzian in the Pedal Right Division, which is also one of only two full-length 64′ stops in the world.”
"The Grand Ophicleide (organ stop) in the Pedal Right Division, speaking on 100" wind pressure, is also recognised by The Guinness Book of World Records as the loudest organ stop in the world. It is described as having "a pure trumpet note of ear-splitting volume, more than six times the volume of the loudest locomotive whistle”. In fact, the Grand Ophicleide produces 130 dB at 1 metre distance.
"The Wanamaker Grand Court Organ at Wanamaker’s department store (now operated by Macy’s) in Philadelphia is the second largest organ based on number of pipes, and the largest in the world based on number of ranks and physical mass weight.It is the largest operational musical instrument in the world, with six manuals, 463 ranks, 399 registers, with 28,677 pipes and weighs 287 tons. The organ was initially constructed by the Los Angeles Art Organ Co. in 1904, and expanded twice by the Wanamaker Organ Shop from 1914–1917, and 1924-1930.It is played twice a day, six days a week, and there are many recordings of this organ.”
"The Grand Organ in the Sydney Town Hall’s Centenary Hall, Australia was for many years the largest in the world. It remains the world’s largest organ without any electric action components and is one of only two organs with a full length 64′ Contra-Trombone stop"
"The Organ of the Basilica of St. Martin (Weingarten), Weingarten, Württemberg, Germany, is built around six church windows, with a detached console facing the church. The tracker action is entirely mechanical, sometimes spanning as much as 20 metres, and going around several corners. It was built by Joseph Gabler during 1713 - 1750.”