According to the Guinness Book of Words, NIIOMTPLABOPARMBETZHELBETRABSB OMONIMONKONOTDTEKHSTROMONT (56 letters, 54 in Cyrillic).
Found in the Concise Dictionary of Soviet Terminology, it means: The laboratory for shuttering, reinforcement, concrete and ferroconcrete operations for composite-monolithic and monolithic constructions of the Department of the Technology of Building-assembly operations of the Scientific Research Institute of the Organization for building mechanization and technical aid of the Academy of Building and Architecture of the USSR
Bonkers