International Space Station can be seen from many locations on the Earth with naked eyes, most probably during the night. It orbits Earth at approx. 400 km / 248 miles above the surface, with speed around 8 km per second / 17 200 mph.
ISS makes one orbit in approx. 90 minutes, so it is possible to spot it as a fast moving bright object in the night sky, that is similar to a plane.