You know that scene in Coco where Miguel crosses the petal bridge from the land of the living to the land of the dead? Well London's got it's own version of that bridge — except it's made of bricks, not petals, and it transports you from London to Surrey. [Insert your own land of the living/dead gags here]
Anyone who's been to Hampton Court Palace will likely have made use of the handsome W. P. Robinson/Edwin Lutyens triple-span crossing, officially opened by Edward VIII in 1933. That's right, the bridge is surprisingly less than a century old — the architects purposefully matched the brickwork and style to the Christopher Wren-designed chunk of the nearby palace.
This is actually the fourth bridge at this location, and before that would have been the rough spot for a Tudor ferry crossing. When built in the 1930s, the bridge crossed the Thames from Surrey on the south bank, to the Middlesex border on the north bank. But overnight on 1 April 1965, the Hampton/Middlesex end was sucked into Richmond upon Thames and Greater London thanks to the London Government Act, while the southerly portion of the bridge stubbornly stayed put in Surrey.
Hampton Court Bridge is the only bridge on the Thames from which you can cross directly over from Greater London into another county. However, it's not the only bridge FULL STOP where you can do that. As pointed out by a sharp-eyed colleague, there are the footbridges across the River Cray from Bexley into Kent — and we'd venture there are other small crossings elsewhere on London's fringes too (if you know of one, tell us in the comments). Arguably, you could count the likes of the M25 across the River Lee near Waltham Cross as another example. Doesn't quite carry the same wide-eyed enchantment as the site of a Tudor palace, though — let alone a Disney Pixar movie.