Friday Funny: The Citywide Crossword Puzzle

"There is one interesting detail about the design of the puzzle. It looks like an empty puzzle during the day-light, but at night when special lights are on the words in the puzzle become visible with a lightly-glowing fluorescent color."

"The questions for this crossword puzzle are located in different point of interests of the city, like monuments, theaters, fountains etc. So people while walking around the city can try to answer the questions and writing down the answers. When the night comes to the city they can meet at this house and check their degree of intelligence."