Andrew V.
Google
Very interesting place from a historical standpoint. The temple structure is largely destroyed unfortunately, and it’s clear that ground settlement is taking a further toll. But it is cool that you can walk over/around it (on sidewalks with railing), unlike some other sites.
The indoor portion of the museum is quite interesting, you could probably spend 1 - 1.5 hours there and cover it well. It’s basically designed with a routed layout where you can walk through and cover everything in order, which I found helpful.
If I had to choose, I would choose Anthropology Museum over Templo Mayor, but hopefully you have time for both.