I spent years running AD&D2e games in the Free City of Greyhawk. I read Fritz Leiber's Lanlhmar books. I am currently reading "Zobeck: Clockwork City", recently purchased, looking for inspiration to run Traveller adventures.
Are there any Traveller equivalents of these cities and their neighbouring polities?
The issue here is that the premise to a campaign like Greyhawk is fundamentally different than the default premise of any Traveller campaign, which is based on Travel. In something like Greyhawk, the players have a base, the referee details the place, people and events over time so the players feel rooted in it, and the adventures are all a few days ride from the city, usually - we'll call this a hub and spoke campaign where the city is the hub.
In Traveller, the hub is usually a ship and the ship moves from place to place, so Traveller uses a journey style campaign. The upside is you get to see somewhere new every few weeks, the downside is almost nowhere is deeply detailed like a city you stay in for literal years of play (Except for the ship, and in Traveller that's usually more of a moving house than a moving city).
That's not to say it cannot be done in Traveller, it absolutely can, but not much of the published material will give you more than a good starting point. There are some interesting possibilities, though.
- The hub is a really big ship, so you're still travelling, but you're on some behemoth of a ship that feels like a city. Star Trek is this kind of campaign - a moving city full of recurring characters that goes from place to place in search of adventure.
- The hub is a space station in a busy place, somewhere near the edge of danger - think Deep Space Nine.
- The hub is a city, but it's adjacent to a world of adventure. Maybe it's a Grav city floating over the jungles of an otherwise primitive world and the players are cops or scouts or members of some organisation that gives them ample excuse to go groundside and get into trouble.
The only thing you can do wrong here is to make it too like Greyhawk - Traveller is about Travel and science fiction adventure in the Far Future. The more static you make it, the more like D&D you play it, the less it matters that you're playing Traveller at all.
Let us know what you decide to do.
PS: The Deepnight Revelation Campaign is a good example of the players living in a Moving City (An Element Class Cruiser) and journeying with a cast of recurring characters on a multi-year mission beyond the edge of known space. This is the closest thing to the Star Trek premise in published Traveller materials.
Not quite what I expected. Hopefully, I'll take the ideas from Zobeck and apply them to the Sindal Subsector in the CRB or possibly elsewhere in the Trojan Reach or even in the Spinward Marches. Merchants, Traders, Militaries, Thieves, Rascals are easy enough to move to a Far Future setting. Wizards can be technologists. Magic items can be high-tech equipment. But I was hoping someone else had already done the work 
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