Grapevine Vintage Railroad in the Ft. Worth area. It leaves from a cute little station in Grapevine and chugs to the Ft Worth Stockyards (or you can ride it the other direction, or take an excursion from there, or get a round trip). The Stockyards are only a few blocks wide but pretty interesting - though a little touristy nowadays. You can adjust how much time it takes or the cost by going one direction and having someone pick you up or taking the open air car if you can take the heat. This is a good activity for little ones or train nuts - our family is full of both!