Canon Square (plac Kanonia), behind St. John's Cathedral, is a small triangular square. Its name comes from the 17th-century tenement houses which belonged to the canons of the Warsaw chapter.Some of these canons were quite famous, like Stanisław Staszic who was the co-author of the Constitution of May 3, 1791. Formerly, it was a parochial cemetery, of which there remains a Baroque figure of Our Lady from the 18th century. In the middle of the square, is the bronze bell of Warsaw, that Grand Crown Treasurer Jan Mikołaj Daniłowicz, founded in 1646 for the Jesuit Church in Jarosław.The bell was cast in 1646 by Daniel Tym - the designer of the Zygmunt's Column. Where the Canon Square meets the Royal Square is a covered passage built for Queen Anna Jagiellon in the late 16th century and extended in the 1620s after Michał Piekarski's failed 1620 attempt to assassinate King Sigismund III Vasa as he was entering the Cathedral. Also the thinnest house in Warsaw is located there.