Sotheby's was founded in 1744 when Samuel Baker held a sale of rare books owned by Rt. Hon. Sir John Stanley, Bart. The firm made its name with auctions of rare or old books and manuscripts and it was only in the 1900s that Sotheby's expanded to include all areas of the fine and decorative arts.
In 1917 Sotheby's moved from its premises in the Strand to the current location on New Bond Street, and today you can pretty much buy anything you like as long as it's really nice and you're loaded: there's coins, furniture, houses, wine, cars, Old Master paintings, and a whole host of other amazing things.
Books are still a great strength however: in 1983, for example, a single book, The Gospels of Henry the Lion went for a staggering £8 million.