Large branches of major banks are usually open from 8am to 7pm and some are open on Saturday mornings. An extensive network of ATM machines is available across the city. Charges for using other bank's machines and fees for international accounts may differ if you are still using your home countries bank. Try not to use ATMs after dark, check to make sure you have enough money before you go out. You can also use your hotel to change money, the rate will not be so favorable, but the transaction will be much safer.
There are three main banks in Mexico and many smaller banks that are also reliable. All Mexican banks are insured by the Mexican government against bank failure. Different banks offer different benefits and monthly charges, so shop around to find the bank that best meets your needs. The three major banks:
Bancor and Bankamex (American Express) are two of the largest banks and have branches in the USA, but many foreigners feel they have excessive fees. These banks offer higher minimums and/or less liquidity, but they pay higher interest. To open an account at either bank, you must do so in person.
Lloyd's is highly received by foreigners. It does not have branches in the US, but they have lower fees than the other two. You may also open a Lloyd's account through the mail. Unlike the major Mexican banks, Lloyd allows transactions by fax, phone, e-mail, or regular mail.
Remember that the accounts are insured in pesos, not US dollars. Protecting yourself by keeping some money in a foreign nation's local currency is not the same as currency speculation. If the peso should lose 10% of its value, prices will rise, but probably not 10%. If the peso rises in value, and/or the dollar declines at the same time, your American dollar will buy less pesos, and this can hurt retirees on a fixed income. It is highly recommended that foreigners keep some of their money in their home countries account.