The 1908 Olympics were originally to be held in Rome, but when Mount Vesuvius erupted in 1906 a new host city had to step forward and so the tradition of cities bidding was born. Berlin and nearby Milan both offered to host the games but London won the bid.
Most of the funding for the 1908 games came from donations made by enthusiasts and the staff included many volunteers, much like this summer's London games. As you can see here though, behind the acrobat, stadium banners have been placed by the Daily Mirror and the Evening News. Advertising was becoming a central part of sporting events.