My husband and I had an extremely interesting visit to the Tower Bridge. We used Tesco clubcard vouchers for our concession entry and thought it excellent value. Just a short walk from London Bridge MainLine Station.
You walk along both sides of the upper part of the bridge and learn the history of its construction as well as seeing many pictures of the area through the years.
There was also a wonderful display of large coloured pictures of various famous bridges from across the world, and at present, pictures and much interesting information about past Olympic Games.
You go right down into the basement to see how the bascules are raised and admire the shiny boilers. A very worthwhile visit.
Ashamed to admit I didn't notice what facilities there were for disabled guests, though I'm sure it would tell you on the website.