It was an historic event.
but we say a hospital.Originally Posted by EMAIL REMOVED - Send PM to This User Instead
We say an hotel even though some people write a hotel. In this case the possible reason is from the French word l'hotel with the little house (^) above the 'o'. The 'h' was 'silent' and remained so in the English use of the word hotel.
There are quite a few examples, for example we say a unicorn, a hospital, etc.
Hope this helps.
P.S. I'm sure the experts here can explain this much better than I have done.