The Ukrainian city of Lvov has recently installed what might just be theworld's largest crossword (in physical size). The puzzle covers the entire side of a residential tower block that's approximately 30 meters tall. During the day the crossword appears empty - with the answers lighting up at night. The questions for the puzzle are located in different point of interests of the city: monuments, theatres, fountains etc. so people walking around the city can try to solve the puzzle and write down their answers. When night comes they can meet at this house and check how they did.