If you happen to be in Prague having only US cash, you should be extremely careful of where you exchange your money to the Czech Kronas. After getting ripped off at a random currency exchange booth I decided to discover the best place to for currency exchange in Prague. Some couple of hours of research and approaching locals about it I found that CSOB bank has the best deal. It charges only 2% commision from the total amount exchanged. Be careful of the small currency exchange booths scattered around Prague. Most of them lure you in by presenting 0% commission signs and confusing verbiage on them mask a very poor exchange rate. If you are tempted to use them, ask what the total amount you will receive before handing over any money, they WILL NOT cancel the transaction after the receipt has been printed, I even called the local Police to revert the transaction but even they couldn’t help. The policeman even showed me a paper with a statement that all transactions are tracked by the Prague’s central bank and they are not to be canceled.
If you need to withdraw money out of an ATM using a US-issued debit card, be aware that most US banks charge at least $3 plus 3% commision from the amount withdrawn for each transaction. So it is best to simly bring cash to Europe and use banks or local exchange offices. Be aware of extremely high theft rate in Barcelona, Spain, so be sure to hide that cash well into inner pockets of your clothes. This city is the Mecca pickpocketers!