Cholula is maybe a 20 minute Uber from the historic center of Puebla, and yes, it has the very biggest pyramid on earth. It is also a lovely town easily navigated on foot, and we spent several hours in the archeological zone, as it is known, walking through the slightly scary tunnels, wandering the ruins that have been excavated, and then took a walk through the ‘downtown’ where we had a delicious lunch and a walk through an odd church right across from the zocalo. It made for a good day trip.
The pyramid was for centuries thought to be a big hill with a church on the top that was built in the 1600’s. A thing about Mexico—it is so much older than the US, with many buildings and churches still standing that were built in the 16th and 17th century. Bits and pieces were unearthed over the last 100 years or so, and now there is even a small museum (very small) that discusses the history of the area, once a marshy lake, and what they have been able to decode about the different groups which lived, died, and moved on over the centuries.