To maximize your puzzling space, click on the Maximize button in the lower right corner of the puzzle screen for fullscreen mode. Click on it again to return to normal mode.

For more tips, see the Online Puzzle Tips page.

Wiener Linien ULF B1 puzzle, based on an original photo by Dariusz Zaruk (photo copyright Dariusz Zaruk -- used with permission). Photographed at Vienna, Austria, August 12, 2012. Click here for more information about this photograph