Thirlestane Castle is a castle set in extensive parklands near Lauder in the Borders of Scotland. The site is aptly named Castle Hill, as it stands upon raised ground. However, the raised land is within Lauderdale, the valley of the Leader Water. The land has been in the ownership of the Maitland family since 1587, and Thirlestane served as the seat of the Earls of Lauderdale. The castle was substantially extended in the 1670s by the first and only Duke of Lauderdale. Further additions were made in the 19th century. The castle is now cared for by a charitable trust, and is open to the public.