By train. Canterbury has two stations. Canterbury West is on the high-speed line from London St Pancras (about 55 minutes) and is the faster option from central London; trains also run from Ashford for connections to Eurostar. Canterbury East is on the slower line from London Victoria (about 90 minutes) and is closer to the cathedral.
By car. Canterbury is just off the M2 motorway, about 90 minutes from central London on a good day. The medieval centre is pedestrianised, so leave the car at one of the Park & Ride sites on the edge of town — there are three, with cheap parking and a regular shuttle bus that drops you near the bus station.
By coach. National Express runs direct coaches from London Victoria to Canterbury bus station (around two hours), often the cheapest option if you book ahead.
From Europe. The Channel Tunnel terminal at Folkestone is 20 minutes by car; Dover for the ferries is about 25 minutes. Canterbury is a natural first or last stop on a southern England loop.