This is on my bucket list to go and see, It's the only place in the world this could happen, as there are usually a couple of deaths a year and it would be banned anywhere else.
the reason its legal to race there is because there are no speed limits on the roads except for in the villages, if you take your roadbike there during tt week you can take it round the roads as they make all traffic one way for the week, topgear car show often take cars there to test them, those simulater rides on hydraulics where you sit in what looks like a space age van had a tt experience and it scares the crap out of you when you think of the speeds involved, i met one of the racers (david jefferies) at a supermoto event he was running and he was saying how much he was looking forward to racing the tt two weeks later, he died in that race when cranked over at 150mph and lost it on someone elses oildown and hit one of those stone walls! he had no chance at all,