Netherlands.
Explanation:
London is the capital of England as well as being the capital of the United Kingdom. It is by far the largest city in the country. London is the most important and most influential city in the United Kingdom in pretty much all sectors, out-shadowing the traditionally important cities and their ability to be its competitors.
This city is located in the southeastern part of the United Kingdom. If we drew a line eastward from London and that line to stretch for 500 miles, than we will pass just north of France and Belgium, and eventually get to the country of Netherlands. More specifically, we will end up in the southwestern part of the nation known for bicycles, tulips, and windmills.
