One of the things here in San Antonio that I found amazing is how they have developed what was less than a mile long "River Walk" in the down town area to a length of about five miles in length. They even have a dam and locks for the River Tour boats so they can navigate the upper reaches of the river. The last addition opened up for traffic less than a year ago.
I took the usual Tour but it only covered the older section of the River Walk. I went back a couple of weeks later an caught one of the Rio Taxis at the northern most location and rode all the way to the southern end of town and got off at the Tower Of The Americas. You can't miss the tower, because it is over 750 feet tall with a rotating restaurant and observation deck.
A person really has to take the tour in person in order to fully appreciate the beauty of the River Walk, but here are a few of over 300 pictures I have taken of the River Walk and tower. I have two slide shows with music on just the River Walk area.