Fact: In terms of buildings, a Cathederal is bigger than a Chapel, and in terms of trains for Wedding dresses the same rule applies (if you happen to find any exception to this, please don't bother writing in!)
A Cathederal, or long, train can fall anything from 2 metres from the back of the skirt and can extend backwards as far as you like - if you are feeling particularly brave, you can even try to beat the 25 foot train that Princess Diana wore!
Exceptionally long trains often tend to be detatchable, although even the shortest Cathederal train can feature this in a bid to increase the practicality of the outfit. For those built-in Cathederal trains, small ties that allow the train to be fastened up are nearly always included.