I agree, at the ATM. Never go to a bank in the USA and ask to exchange dollars for euros. It will be a rip off. The only thing worse would be going to one of the Thomas Cook Foreign Exchange booths at the airport to convert your money.

There was an interesting TV story about this. A reporter went to the airport exchange booth with $100. He kept going back and forth exchanging dollars for euros then euros for dollars. With the seventh exchange he was broke, the $100 was all consumed in transaction fees.

At an ATM there is a usually a per transaction fee charged by the european bank and by your bank. That means it's best to take out all of the money you will need for your entire trip if you don't want to be hit with multiple transaction fees.

If you will ever go back to Europe it's probably a wise investment to take out a lot of euros by going to a bank there. I moved to Venice in 2010 when the exchange rate was 1.48 to 1.00, meaning that I paid 48% more for everything. Last week it was only 1.07 to 1.00, but it's going up and right now it's about 1.10 to 1.00. The dollar was getting so cheap over there that when it went down to 1.25 to 1.00 I bought a bunch of euros at that price, never thinking it would get down to 1.07. Obviously a mistake. But right now the euro is at an almost historic low. If you are ever going back to Europe it may be a good idea to just go to a bank and buy a lot of euros.

An ATM or USA credit card will always charge you the exact, official, published exchange rate. No chance of getting ripped off. The ATM or credit card will always get you the best rate. Some unscrupulous stores and restaurants will ask, "do you want to pay in dollars or in euros?" Always say in euros so that your credit card will give you the exact, proper exchange rate. Otherwise, the restaurant or store will just impost their own exchange rate, and it will be usurious.

The only problem is foreign transaction fees. If it's $5 per transaction, then instead of taking out $100 five times and paying 5%, just take out $1,000 one time and pay 0.5%.

This won't work if you are never going back to Europe and you return with 100 euros and have to pay an outrageous Thomas Cook exchange fees to convert back to dollars. Just figure out what your transaction fees are, and calculate your spending.

If you don't have a credit card without transaction fees just go to the ATM at the airport and take out as much money as you can, which will probably be 200 euros or else the machine will balk, and you'll be fine. Sometimes I call my bank beforehand and tell them I want that limit stretched so that I can take out 500 euros at a time, and they do it. I have a credit card without foreign transaction fees but in some of the areas that I go to like a coffee shop, they only take cash.

In sum, if you have a credit card that will charge you 4-5% with each transaction, just go to an ATM and see how much they charge. It's usually per transaction, so estimate and take out all the money you need at one time, and pay cash. You will have no trouble whatsoever taking euros out of an ATM machine at MXP in order to pay for your taxi into the city. You'll probably get hit with $5 in withdrawal fees.