London is the capital and largest city of England and the United Kingdom. The city stands on the River Thames in the south-east of England, at the head of its 50-mile (80 km) estuary leading to the North Sea. The City of London, London's ancient core and financial centre − an area of just 1.12 square miles (2.9 km2) and colloquially known as the Square Mile − retains boundaries that closely follow its medieval limits.

Singapore is a sovereign island city-state in maritime Southeast Asia. It lies off the southern tip of the Malay Peninsula, bordering the Straits of Malacca to the west, the Riau Islands to the south, and the South China Sea to the east. The country's territory is composed of one main island and 63 satellite islands and islets. It has the second greatest population density in the world.