Teotihuacan pyramids is a must if you are around Mexico-city (or simply DF as locals call it).
It’s just an hour or hour and a half ride by bus. You can catch a bus either at Terminal Norte (and there you can get either by subway (Autobuses del Norte station, line #5) or Indios Verdes (and it’s right at the end of subway line #3). Termonal Norte is a bit more comfi to reach but then if you hit traffic inside the city – it can add another hour to your trip.
If you choose Terminal Norte, then when you get there (it’s right across the street from the subway) ask for “Piramides” and you’ll be pointed the right ticket office.
If you prefer Indios Verdes, then you need exit J from the subway. You will see a line of buses, you’ll need to walk a bit along them and at some point (a minute or two walking) you’ll see a bus with a sign “Piramides”. Ask to drop you at the pyramids, but in case the driver will forget you can recognize the place easily: when you reach a roundabout full of various cactus – that’s the place you need to get down. That’s right next to the entrance #1.
Bus ticket costs 35-45 pesos one way.
Entry fee is 65 pesos for foreigners. You’ll get a discount (half the price) if you are a student at one of Mexican universities but don’t forget your student ID card.
It’s really better to go to Teotihuacan on weekdays as you won’t hit the crowd like on weekends and there is pretty big chance to be almost alone at the ruins. And of course it’s better to arrive early as there is not that much shadow (though you always might find a tree behind the pyramids) and it’s getting pretty hot by the noon.
Take sunscreen and a hat. They would be very useful! Tough it also might be chilly in the morning, so a jacket is a good idea as well.
The working hours are 9am-5pm, Teotihuacan is open every day.
There are little stores with water and snacks as well as souvenirs at almost any entrance (though sellers appear a bit later than the opening of the park). Bathrooms are nasty and dirty but go ahead if you really need to use it.
You will need an hour minimum to climb both pyramids (pyramid of the Sun and pyramid of the Moon), walk Avenue of the Dead, take some pics and spend a bit on top. But the place is really cool to sit for a while on top of pyramids, you easily can stay for an hour on top of each pyramid if you are in meditation or observation.
For photographers: keep in mind that it’s forbidden to use tripod at the sight.
To get back to Mexico-city, go to the exit #2 – it’s right in front of pyramid of the Sun (the one you can climb to the top). You will get to the road when the line of the stores will finishes – cross it and that’s the bus station. Buses pass every 15-20 minutes. Though if you need a particular station – ask if it goes there. If you don’t care where to get out (at Indios Verdes or Terminal Norte) then any will fit you.
Teotihuacan is an amazing place and great for a half day trip. But it’s always possible that you will hit traffic, so be prepared to spend more time in the bus.