London is the capital city of the United Kingdom.
After leaving Themyscira, Steve Trevor and Diana arrived in London to show Doctor Poison's notebook to the British War Council. However, they dismissed the idea of a mission in German territory. Soon, the Wonder Men formed themselves and they were supported financially by Sir Patrick Morgan.
Decades later, in 2017, a small group of reactionary terrorists known as the Black Clad took over the Old Bailey Courthouse, taking several hostages including a school field trip. Wonder Woman stormed the building, using the Lasso of Hestia to compel one of the terrorists to tell her their plans. She was then able to take out the terrorists and neutralizes the bomb.