Image by Image Editor via FlickrIs it at the North Pole, South Pole, or somewhere in Pluto. According to this report, the coldest spot in the solar system is on our moon. It is in the moon's South Pole in the crater that is never being exposed to the sun. It is colder than far away Pluto.
Temperatures there were measured at 397 degrees (minus 238 Celsius) below zero. That's just 35 degrees (2 Celsius) higher than the lowest temperature possible.
NASA is making the first ever map of the moon. I am not sure whether, NASA has managed to cover everywhere in the solar system. If not, there might be some other locations that will be the coldest.