About Time: Where three time zones meet
23 March 2011 Last updated at 16:38 GMT
Theoretically, the world should be divided into 24 equal time zones, in which each zone differs from the last by one hour. But as the years have passed, the world has turned into a much more complicated place.
Time zones are now much more irregular and sometimes seem positively eccentric, affected as they are by political, geographical and social changes in the real world.
Add to that arguments over daylight saving, and you have a subject that has been the cause of furious debate around the world.
Many places in the world are the meeting point of two time zones - but in the Arctic Circle, there is a very unusual situation. It is where the three time zones of Russia, Norway and Finland meet - and as Andy Brownstone discovered, it is not an easy place to get to.