The Pennsylvania State Capitol is often referred to as a "palace of art" because of its many sculptures, murals and stained-glass windows, most of which are Pennsylvania themed or were made by Pennsylvanians.[4] The building was listed on the National Register of Historic Places in 1977 and designated a National Historic Landmark in 2006; the boundaries of the designation were expanded to include the Capitol Complex in 2013 with the capitol as a contributing property.