Crystal City

The Crystal City was famous for its elegance in construction, and the scientific minds that hail from it.

''“ I remember it. The most spectacular city on Cybertron. ” '' — Optimus Prime

Cartoon Canon
Millions of years ago, the Crystal City was one of the most beautiful structures on all of Cybertron. It was built by the Constructicons (including, at one point, Hauler) and protected by a Guardian Robot named Omega Supreme. Omega and the Constructicons were dear friends, although they didn't get to visit him and the city very often.

Tragically, the very Constructicons who created this masterpiece were responsible for its destruction. They were ambushed by Megatron and his Robo-Smasher, which turned them evil. Under his orders, they lured Omega Supreme away from the Crystal City with a false story of a nearby Decepticon attack. He was reluctant to leave his post, but took the Constructicons at their word when they promised to protect the city in his absence. Once he was gone, they razed the structure to the ground.