From the official site:
Starting in the gardens of the Palace of Versailles and ending at the bottom of the Eiffel Tower, the 45km Trail is a good opportunity to take things a step further for those who finished the 30km Trail in the previous editions. This nature race course can also be a great transition for marathon enthusiasts who want to switch to medium-distance trail running.
Unfortunately I was not able to participate due to my sprained ankle.
Next year hopefully!