The architecture of Copenhagen in Denmark is characterised by a wide variety of styles, progressing through Christian IV's early 17th century landmarks and the elegant 17th century mansions and palaces of Frederiksstaden, to the late 19th century residential boroughs and cultural institutions to the modernistic contribution of the 20th century such as Arne Jacobsen's National Bank and SAS Royal Hotel. Since 2000 Copenhagen has seen a boom in modern architecture with notable contributions both by leading international architects and a wave of new successful Danish architects.