Crystal City

Crystal City is the G1 cartoon's one great architectural tragedy, and its story is told entirely in flashback in the season two episode The Secret of Omega Supreme. Millions of years before the war reached its modern form, the Constructicons and their teammate Hauler were builders, not soldiers, and Crystal City was their masterpiece: the most beautiful thing on the planet. Omega Supreme, then a Guardian robot, was their friend and the city's protector, and the episode goes out of its way to show them as a genuinely warm group.

Megatron destroys that with the Robosmasher, a device that rewrites a Transformer's loyalties. The Constructicons are captured and reprogrammed into Decepticons, and Megatron's first use of them is exquisitely cruel: they trick Omega Supreme into leaving his post, and while the Guardian is away they demolish the city they built. Omega returns to find his friends gone, his charge destroyed and his purpose voided in a single day. His response is to have himself rebuilt as a weapon and dedicate his existence to killing Megatron, which is why the character behaves the way he does in every subsequent appearance.

Crystal City is the closest the cartoon ever comes to explaining why anyone would hate the Decepticons personally rather than politically. It also quietly rewrites the Constructicons from a toy gimmick into the war's saddest casualties. Later continuities gave the city a different fate, most notably in the Exodus novel where Shockwave's Devastator smashes it open, but the cartoon's version stands alone.

• The Secret of Omega Supreme is one of the earliest G1 episodes to establish that Transformers existed on Cybertron for millions of years before the show's present day.
• Hauler is a Constructicon-era character who never appears again; a vehicle resembling Grapple's alt mode called Hauler is also glimpsed early in season one.
• Crystal City is destroyed in almost every continuity that names it, which has become a running joke in the fandom.
• The Robosmasher is the cartoon's answer to why the Constructicons are Decepticons at all, given that combining teams were originally sold as construction equipment.