Tower Bridge is known to everyone (I think) It is an icon of London. Many people may not be aware there is a museum within the Bridge.
An iron frame bridge is clad in stone to hide the bridge frame and workings. Inside the working of the bridge are old boilers engines and vast girders riveted together.
You can walk across the river high above the road way the only disappointment was that these walkways are enclosed today in glass so you do not get the feel of the wind high above the River Themes (but there were some windows you could open to take pictures out of)