For this achievement you'll need to build the Hall of Charioteers as an High Elf faction in the city of Tor Anroc. This can be done in both the Eye of the Vortex and Mortal Empires campaign.
The city of Tor Anroc is part of the Tiranoc region, which in turn is part of Ulthuan, the island of the High Elves.
Start as a High Elf faction and conquer the city of Tor Anroc with an army or confederate the Tiranoc faction. Upgrade the city to lvl 3 and build the Hall of Charioteers. When the building is complete the achievement should unlock.