Banks -- Banks are usually open Monday through Friday from 9am to 4pm (some later); many offer Saturday business hours, typically from 8am to 3pm. Bank branches at the airport are open whenever the airport is busy, including weekends. They usually offer ATMs and decent rates of exchange. Banks and money-exchange offices line Avenida Reforma. The Centro Histórico downtown also has banks and money-exchange booths on almost every block, as does the Zona Rosa.

Currency Exchange -- The alternative to a bank is a currency-exchange booth, or casa de cambio. These often offer extended hours, with greater convenience to hotels and shopping areas, and rates similar to bank exchange rates. Usually, their rates are much better than those offered by most hotels. Use caution when exiting banks and currency exchanges, which are popular targets for muggings.

Drugstores -- The drug departments at Sanborn's stay open late. After hours, check with your hotel staff, which can usually contact a 24-hour drugstore.

Elevation -- Remember, you are now at an elevation of 2,239m (7,344 ft.) -- over a mile in the sky. There's a lot less oxygen in the air than you're used to. If you run for a bus and feel dizzy when you sit down, it's the elevation. If you think you're in shape but huff and puff getting up Chapultepec Hill, it's the elevation. If you have trouble sleeping, it may be the elevation. If your food isn't digesting, again, it's the elevation. Some people even find themselves getting inebriated more quickly than they would at lower elevations. There is not much you can do to help your body adjust -- it takes 3 days or so to adjust to the scarcity of oxygen. Go easy on food and alcohol your first few days in the city.

Embassies & Consulates -- Most countries have their embassy in Mexico City.

Emergencies -- The Mexico City government has an emergency number for visitors -- dial tel. 060 for assistance 24 hours a day; have a local or Spanish speaker help you. SECTUR (Secretaría de Turismo; tel. 078; staffs telephones 24 hours daily to help tourists in difficulty. In case of theft, you can contact Quejas de Turistas Contra Robos (tel. 55/5592-2677). A government-operated service, Locatel (tel. 55/5658-1111), is most often associated with finding missing persons anywhere in the country. With a good description of a car and its occupants, they'll search for motorists who have an emergency back home.

Hospitals -- The American-British Cowdray (ABC) Hospital is at Calle Sur 136, at the corner of Avenida Observatorio, Col. las Américas (tel. 55/5230-8000;

Internet Access -- It is easier to find cybercafes in some resort areas than in Mexico City. However, most hotels that cater to business travelers offer Internet connections in their business centers. The Internet Café, Rep. de Guatemala 4, connected to the international youth hostel in the Centro Histórico (tel. 55/5618-1726), is open daily from 7:30am to 10pm. The price per hour of access is 12 pesos. Many cafes offer free Wi-Fi for customers; just ask for the code and order at least a cup of coffee.

Pollution -- The rainy season, usually lasting from May to October, has less pollution than the dry season. Mid- to late November, December, and January are noted for heavy pollution. During January, schools may even close because of it, and restrictions on driving that are usually imposed only on weekdays may apply on weekends; be sure to check before driving into or around the city. Be careful if you have respiratory problems. Just before your visit, call the Mexican Government Tourist Board office nearest you and ask for the latest information on pollution in the capital. Minimize your exposure to fumes by refraining from walking busy streets during rush hour. Make Sunday, when many factories are closed and many cars escape the city, your prime outdoor sightseeing day.

Post Office -- The city's main post office, the gorgeous Correo Mayor, is a block north of the Palacio de Bellas Artes on Avenida Lázaro Cárdenas, at the corner of Tacuba. For general postal information, call FonoPost (tel. 55/5385-0960); the staff is very helpful, and a few operators speak English.

If you need to mail a package in Mexico City, take it to the post office called Correos Internacional 2, Calle Dr. Andrade and Río de la Loza (Metro: Balderas or Salto del Agua). It's open Monday through Friday from 8am to noon. Don't wrap your package securely until an inspector examines it. Although postal service is improving, your package may take weeks, or even months, to arrive at its destination.

Restrooms -- There are few public restrooms. Use those in the larger hotels and in cafes, restaurants, and museums. You might want to carry your own toilet paper and hand soap depending on what neighborhood you're in. Many public restrooms at museums and parks have an attendant who dispenses toilet paper for a "tip" of 5 pesos, in lieu of a usage charge.

Safety -- In response to rising crime, Mexico City has added hundreds of new foot and mounted police officers, and there's a strong military presence. But they can't be everywhere. Watch out for pickpockets. Crowded subway cars and buses provide the perfect workplace for petty thieves, as do major museums (inside and out), crowded outdoor markets and bullfights, and indoor theaters. The "touch" can range from light-fingered wallet lifting or purse opening to a fairly rough shove by two or three petty thieves. Be extra careful anywhere that attracts a lot of tourists: on the Metro, in Reforma buses, in crowded hotel elevators and lobbies, at the Ballet Folklórico, and at the Museo Nacional de Antropología.

Robberies may occur in broad daylight on crowded streets in "good" parts of town, outside major tourist sights, and in front of posh hotels. The best way to avoid being mugged is to not wear any jewelry of value, especially expensive watches. If you find yourself up against a handful of these guys, the best thing to do is relinquish the demanded possession, flee, and then notify police. (You'll need the police report to file an insurance claim.) If you're in a crowded place, you could try raising a fuss -- whether you do it in Spanish or English doesn't matter. A few shouts of "¡Ladrón!" ("Thief!") might put them off, but that could also be risky. Overall, it's wise to leave valuables in the hotel safe and to take only the cash you'll need for the day, and no credit cards. Conceal a camera in a shoulder bag draped across your body and hanging in front of you, not on the side.

If you think you've been ripped off on a purchase, call the consumer protection office (Procuraduría Federal del Consumidor; tel. 01-800/468-8722 or 55/5625-8722;

Telephones -- Telephone numbers within Mexico City are eight digits; the first digit of the local phone number is always 5. Generally speaking, Mexico City's telephone system is rapidly improving (with new digital lines replacing old ones), offering clear, efficient service. Some of this improvement is resulting in numbers changing. As elsewhere in the country, the telephone company changes numbers without informing the telephone owners or the information operators. Business telephone numbers may be registered in the name of the corporation, which may be different than the name of a hotel or restaurant owned by the corporation. Unless the corporation pays for a separate listing, the operator uses the corporate name to find the number. The local number for information is tel. 040, and you are allowed to request three numbers with each information call. When dialing a mobile from within the country, dial 044 before the 55.

Coin-operated phones are prone to vandalism; prepaid Ladatel card-only Telmex phones have replaced most of them. Ladatel cards are usually available at pharmacies and newsstands near public phones. They come in denominations of 30, 50, and 100 pesos.

Weather & Clothing -- Mexico City's high altitude means you'll need a warm jacket and sweater in winter and even on some chilly summer nights. The southern parts of the city, such as the university area and Xochimilco, are much colder than the central part. In summer, it gets warm during the day and cool (but not cold) at night. From May to October is the rainy season (this is common all over Mexico) -- take a raincoat or rain poncho. People tend to dress somewhat conservatively in Mexico City; neither shorts nor short skirts are common.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.