The Singel is a canal in Amsterdam which encircled the city in the Middle Ages. It served as a moat around the city until 1585, when Amsterdam expanded beyond the Singel. The canal runs from the IJ bay, near Central Station, to the Muntplein square, where it meets the Amstel river. It is now the inner-most canal in Amsterdam's semicircular ring of canals. Other Dutch towns also have ring-shaped canals named Singel.
Ace of Hearts, F. Piatnik, Austria, around 1930.
Lutherse Kerk ("Round Lutheran Church"), also known as
Koepelkerk or Nieuwe Lutherse Kerk, built in 1668-1671.
Ace of Spades, Rijnen Reclame, Netherlands, 2002.