From 1959 to 1966 the British Museum (now the British Library) published its General Catalogue of Printed Books. Photolithographic Edition to 1955 in 263 folio volumes from 1959 to 1966. These volumes reproduced the catalogue cards of 4,350,000 items. In 1971 and 1972 the BM issued a Ten-Year Supplement, 1956-1970 in 23 volumes. This set of nearly 300 folio volumes was the "most voluminous" printed catalogue of a single library ever published in print.
Breslauer & Folter, Bibliography: Its History and Development (1984) no. 109.
Between 1967 and 1980 Readex Microprint of New York issued the Compact Edition of the entire British Museum Catalogue in a microprint edition (8 or 10 volumes in one). This was complete in 37 volumes, occupying 7 feet of shelf space. When it was published this was widely viewed as a very valuable reference source, and many antiquarian booksellers, such as myself, bought it. However, I don't think we ever got much use out of it, and it was one of the first large sets we sold when it was evident that online resources would replace sets of this kind. In November 2013 the value of the Microprint Edition was limited. A colleague, Ian Jackson, offered a set for $100 in Cedules from a Berkeley Bookshop, No. 28. (Readex Microprint evolved into Readex, an online publisher of mainly of historical source materials in digital form.)