The London Borough of Greenwich lies on the south bank of the Thames. Rich in maritime history, Greenwich also has an outstanding architectural heritage. Many of its buildings are designed by well known English architects, including the Royal Naval College, the National Maritime Museum and the Royal Observatory built by Sir Christopher Wren for King Charles II. At the Royal Observatory visitors can stand astride Longitude Zero with one foot in the eastern and the other in the western hemisphere. The borough enjoys many royal connections and within its boundaries are two former Royal Palaces and two royal dockyards. Additional visitor attractions include Greenwich Market, the Cutty Sark - the oldest surviving tea and wool clipper, The O2 and the Thames Barrier. Greenwich can be reached in 15 minutes by train from central London, or via a leisurely 45 minute cruise from Westminster or Charing Cross Piers.