Devonshire House in Piccadilly, was the London townhouse of the Dukes of Devonshire during the 18th and 19th centuries. Following a fire in 1733 it was rebuilt by William Cavendish, 3rd Duke of Devonshire, in the Palladian style, to designs by William Kent. Completed circa 1740, it stood empty after the First World War and was demolished in 1924. Many of Britain's great noblemen maintained large London houses that bore their names. As a ducal house (only in mainland Europe were such houses referred to as palaces), Devonshire House was one of the largest and grandest, ranking alongside Burlington House, Montague House, Lansdowne House, Londonderry House, Northumberland House, and Norfolk House. All of these have long been demolished, except Burlington and Lansdowne, both of which have been substantially altered. Today the site is occupied by a namesake modern office building. The site Devonshire House occupied the site of Berkeley House, which was built between 1665 and 1673 and at a cost of over £30,000, by John Berkeley, 1st Baron Berkeley of Stratton, of Bruton Priory in Somerset, following his return from service as Viceroy of Ireland. The site is memorialised today by Berkeley Square, Berkeley Street, Stratton Street and Bruton Street. The house was later occupied by Barbara Villiers, Duchess of Cleveland, one of the celebrated mistresses of King Charles II. Berkeley House, a classical mansion built by Hugh May, having been purchased in 1696 by William Cavendish, 1st Duke of Devonshire, was renamed "Devonshire House". As part of the agreement, John Berkeley, 3rd Baron Berkeley of Stratton (c. 1663–1697) undertook not to build on that part of the land he retained which lay directly behind the house to the north, so preserving the Duke's view. This covenant was still in force when the Berkeley land was developed after 1730, and the gardens of Berkeley Square represent the northern termination of that undeveloped strip, combined in the south with the gardens of Lansdowne House. On 16 October 1733, whilst undergoing refurbishment, the former Berkeley House was completely destroyed by fire, despite firefighting efforts by the Regiment of Guards, whose barracks were nearby, led by Willem van Keppel, 2nd Earl of Albemarle, and by other local troops led by Frederick, Prince of Wales. The cause was attributed to careless labourers. Ironically, the Duke's former London residence, Old Devonshire House, at 48 Boswell Street, Bloomsbury, survived both its successors until The Blitz