This is an interesting question. Historically, London has played an important role in the development of theatre, and has a high concentration of theatres. However, many other places, particularly traditional tourist resorts like Blackpool and Torquay, have theatres, too. New theatres, like Milton Keynes Theatre, are built in ares where there is enough space for a new building, but in London there just isn't room for new developments of the size needed for a new theatre. It is logical that, with London covering such a small area of the UK, most theatres will be outside London. London has over 40 theatres, and it's West End is still considered to be the home of theatre in the UK. The same holds true globally, as well. People all over the world enjoy the arts, so have built theatres. In the same way that we can say there are more theatres outside London than in London, we can also say that there are more theatres outside New York than in New York, or anywhere of your choice.
because most people lived and worked there in the times they were built.
Most of the English playhouses were built outside of the actual city of London, either in Bankside (Southwark) to the South, or in various places to the North, to avoid the laws of the city.
There was one Globe Theater, Located in London, specifically on Bankside in Southwich.
The Globe
The schedule of musicals at some of the London's popular theaters can be found at various websites like London Theater Guide and Official London Theater.
The London Eye was built for the year 2000 Millennium celebrations and is now one of London's most popular tourist attractions.
The Romans built the first fortifications on the sight (some of which can still be seen) but most of what is standing today was built by the Normans.
Probably the Globe in London, but it is the most famous, and as far as anyone is aware that is the earliest
There are many cenotaphs throughout the UK. The most famous one is in London in the street called Whitehall.
Harry Potter and the Deathly Hallows Part 1 is currently available for viewing at most movie theaters and some Imax theaters.\
Many ancient Greek cities built their own theaters. The most famous is the Theater of Dionysus in Athens.
The London Eye was built for the year 2000 Millennium celebrations and has now become one of London's most popular tourist attractions.