York's National Railway Museum – the biggest in the world, with more than 100 locomotives – is well-presented and crammed with fascinating stuff. It is laid out on a vast scale and is housed in a series of giant railway sheds – allow at least two hours to do it justice. The museum also now includes a high-tech simulator experience of riding on the Mallard (£4), which set the world speed record for a steam locomotive in 1938 (126mph).
Highlights for trainspotters include a replica of George Stephenson's Rocket (1829), the world's first 'modern' steam locomotive; the sleek and streamlined Mallard; a 1960s Japanese Shinkansen bullet train; and an exhibition dedicated to the world-famous Flying Scotsman, the first steam engine to break the 100mph barrier (now restored to full working order and touring the UK). There's also a massive 4-6-2 loco from 1949 that's been cut in half to demonstrate how it works (daily talk at 4pm).
Even if you're not a rail nerd, you'll enjoy looking through the gleaming, silk-lined carriages of the royal trains used by Queens Mary, Adelaide and Victoria and King Edward VII.
The museum is about 400m west of the train station. A road train (adult/child £3/2) runs between the minster and museum every 30 minutes from 11am to 4pm, weather permitting.