The first house at Bowood was built circa 1725 on the site of a hunting lodge, by the former tenant Sir Orlando Bridgeman, 2nd Baronet, who had purchased the property from the Crown. His grandfather Sir Orlando Bridgeman, Lord Chief Justice of the Common Pleas, had previously been granted the lease by Charles II. Bridgeman got into financial strife, and in 1739 under a Chancery Decree, the house and park were acquired by his principal creditor Richard Long. In 1754 Long sold it to the first Earl of Shelburne, who employed architect Henry Keene to extend the house. The 2nd Earl, Prime Minister from 1782 to 1783, was created Marquess of Lansdowne for negotiating peace with America after the War of Independence. He furnished Bowood and his London home, Lansdowne House, with superb collections of paintings and classical sculpture, and commissioned Robert Adam to decorate the grander rooms in Bowood and to add a magnificent orangery, as well as a small menagerie for wild animals where a leopard and an orangutan were kept in the 18th century. Adam also built a fine mausoleum for the 1st Earl in the park.
In the 1770s the two parts of the house at Bowood (the "Big House" and the "Little House") were joined together by the construction of an enormous drawing room. During World War II, the Big House was first occupied by a school, then by the Royal Air Force. Afterwards it was left empty, and by 1955 it was so dilapidated that the 8th Marquess demolished it, employing architect F. Sortain Samuels to convert the Little House into a more comfortable home.