Speaking as a casual visitor with no deep knowledge of the area. In the downtown there is the Riverwalk, which was somewhat rundown when we were there last and the Alamo. The Alamo is much smaller than you imagine it to be. One day will do both. There is also a Mission in that area which we have not visited and some other missions in the area if you are interested in them.
There is a SeaWorld there too which we visited with our son when he graduated from USAF boot camp, I'm not a Sea World aficionado but it seemed to be about the same as the one in Orlando.
I'm sure there are more things to see but we didn't.
Arctic Fox 25Y Travel Trailer
2018 RAM 2500 6.7L 4WD shortbed
Straightline dual cam hitch
400W Solar with Victron controller
Superbumper