Buckingham Palace:

The house which forms the architectural core of the palace was built for the first Duke of Buckingham and Normanby in 1703 to the design of William Winde. The style chosen was of a large, three-floored central block with two smaller flanking service wings. Buckingham House was eventually sold by Buckingham's descendant, Sir Charles Sheffield, in 1761 to George III for £21,000. Sheffield's leasehold on the mulberry garden site, the freehold of which was still owned by the royal family, was due to expire in 1774.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". How much did George III pay for the house?
£21,000