Erath was a planet in RealSpace. It had a moon, Anul.
The Universal Machine lived inside Erath. There it built a Downtime Gate, meant to open into the next universe, and sent through City-born colonists.
The "Car Park" was what UniMac called one cavern, which contained instances what it described as the "useful" human forms of transport, including (but not remotely limited to): stagecoaches, steam-trains, flying carpets, biplanes, monorails, moledelvers, dog-carts, dinghies, agee discs and harnesses, in-comb cars, a-voiders, penny-farthings, chariots, a well-stocked aircraft carrier, amphibious tanks, donkeybots, tractors, timecars, ornithopters, hang-gliders, paddle-steamers, rockets, flighters, shuttlecraft, broomsticks, sleds, aircars, traction engines, hovermopeds, harness-wings, floats, coffin-capsules, rafts, wallcrawlers, juggernauts, metallipedes, a generation starship built into an asteroid, junks, schooners, hypertransports, tunnellers, pagoda-pods, kayaks, airliners, skateboards, chronic jaunting trousers, skis, steam-powered elephants, land ironclads, perambulators, seven-league boots, flying saucers, traffic-stalkers, nuclear submarines, and railway pumping-trolleys. (PROSE: Of the City of the Saved...)