What to do in Houston for a few days?!

Hi All!

I'll be in town for the Houston Marathon Saturday evening, Sunday, Monday, and Tuesday. The weather looks great for the marathon, but maybe not for doing a ton of outdoor activities on Monday & Tuesday. Wondering what some locals would recommend doing/seeing/eating if you only had a couple days here. I will likely not make it to Houston again, so I want to make the best of it! I should be able to walk fine.