Just returned from Prague, Czech Republic. No trains from the airport, but we took bus 100 to the nearest Metro station, then metro into the city, close to our hotel.
From almost anywhere in the city you can get a tram or metro to almost anywhere else! We bought a 7 day ticket which covered all city buses, trams and metro for 280 Kr (about £7) for unlimited travel. Great value for a superb transit system. Clean, fast, regular, easy to use.
