Terra Alta (Catalan pronunciation: [ˈtɛrə ˈaɫtə], locally: [ˈtɛra ˈaɫta]) is a sparsely populated inland comarca (county) in Catalonia, Spain. Its capital is Gandesa. It is also known as Castellania, a name dating back to its medieval status as a fiefdom held by the Order of Knights of the Hospital of St.