A pyramid in the middle of the city!
The location of the Templo Mayor means that there's no excuse for missing it - right in the middle of town, near the Cathedral, the Govt. bldgs and the Zocalo. If you don't have time to travel to Teotihuacan, this will give you a small taste of a pyrimid ruin site. The tour is not long, but it amazing to see the ruins of such a prominent structure, with its many rebuilt walls, that was only excavated in the past few decades.