The one all phills say is london bridge is tower bridge. London bridge is not so exciting to look at but has a great view from if of tower bridge.

My wife and her Family love to wind me up about that when ever it appears on tv

One hint try to use bus routes to see london far better than the tube.
Even better is to walk central london is small and a well planned route will let you see some beautiful buildings,parks,squares, streets and avoid the crowds.

Many routes just go on tfl website to plan the routes or ask on here.

Unless your rich or have to have a person tell you which buliding is which then save your money on bus tours.

A bus pass or travel pass is far cheaper so you can save some money for snacks.

If you need to save money or just sensible go to the sandwich bars where workers go not the chain names. Your get far better deal

Struton street in victoria has loads if you go after the big rush many are selling the sanries off at a discount after 3 when the workers are finished.

Same around goodge st if you go to the side roads where the workers are your get better deals.

Another thing to remeber is there are tesco and sainsburys mini shops everywhere even in traflgar square which are geared up to on the go snacks for workers so you can buy snacks and get your points.

Also many of the people you see using the rail way station fast food places are either rich crazy or know no better. Many workers including me have a 20 percent discount card which reduces the cost to a normal burger king etc so they look busy with regulars but warning they may not be paying what you are..

In the summer if staying in London wake up extra early and you will get to see many of the Famous sights in the centre of London almost empty with just commuters passing by or hanging around bored waiting for their workplace to open up. Many who will happily point people in the right direction, bus routes and what have you. I was sat in hype park corner this morning with two colleuages early morning and happily helped people navigate there way though (its a bit of a maze if you not used a few times).
People today saw one of the great commute route sites in london the mass of cyclists going though the arch on the corner the hustle and bustle of working london.
I always think London doesn't seem quite the same on a non work day with all the coming and goings.

If you go round the same sites a few hours later the hoards of tourists make it almost unbearable.