Also available hand-tinted http://sanfranciscoimages.blogspot.com/2011/12/story-of-tree-in-union-square.html Since 1880, a magnificent tree has adorned the Square in an annual tradition credited to Emperor Norton, the City's first great eccentric. The Square's name originated from pro-Union rallies held on the eve of the Civil War. Built on a sand dune, the Square became a public park in 1850. source: Oakland Public Library, photographer unknown