The answer to this depends on the type of compass watch you have. Most digital compass watches come with a built-in magnetic sensor that allows them to work anywhere in the world. Analog watches, on the other hand, may not work as well in urban areas where there is a lot of interference from buildings and other man-made structures. If you are looking for a compass watch to use in the city, I recommend getting a digital one. Most manufacturers, however, advise that you use the compass function of your watch in an open area away from buildings, vehicles, and other things that could cause magnetic interference, thus affecting the accuracy of the compass.