There are two companies offering discount cards for visitors to Prague. You can buy a special tourist card for visitors called a Matilda card (Prague Card) which provides entry to most major attractions for significantly reduced rates plus free city transport for a fixed price of 690 CZK for adults and 560 CZK for children and students. This card is valid for 3 days. Similarly there is the Passport Card. You can buy both of these at PIS tourist information offices and other tourists spots or at AMEX branches. If you are planning to see some tourist attractions and will be using public transport then these are good value for money.