Excellent museum that needs to be visited many times to absorb everything. I visited on the first day of 2020 and the lines were not too long. After marveling at the huge fountain near the entrance, I started in a clockwise manner. On your left, first quickly go through the North of Mexico and oriental rooms which are important but not as impressive or grand as Maya/Aztec/Olmec rooms.
Do not miss:
Anything in the Mayan room.
Olmec colossal heads
Mortuary mask of Kinich Janaab Pakal
Mask of Malinaltepec
We started at 1200 and by 1800, our brains were overwhelmed with the staggering amount of information. We had limited time, but if you are lucky enough to visit this place more than once, then try to concentrate on 1 or 2 rooms on every visit.
There is a good cafe but get there early(by 1300) to avoid long waiting times.