Dartmoor is an area of moorland in Devon, in South-West England. The moorland is capped with many exposed granite hilltops known as tors, providing habitats for Dartmoor wildlife. The entire area is rich in antiquities and archaeology (Wikipedia).
The Burrow is located only about 30 miles from Dartmoor, so the World Cup was actually held quite close to the Weasley's home. However, with magical travel being what it is, how close something is doesn't make all that much difference.