From the official HP wiki:
The Quidditch Trillenium Stadium, known also as the Quidditch World Cup Stadium was built for the 422nd Quidditch World Cup in 1994. Built in the middle of a large deserted moor in Dartmoor, the Quidditch stadium was capable of holding 100,000 wizards at once, with halls draped in scarlet.
But about the campsite in the movie:
For the film adaptation of Harry Potter and the Goblet of Fire, scenes at the Quidditch World Cup Campsite were filmed at Beachy Head, in Eastbourne, East Sussex. Beachy Head is known for its chalk sea cliffs, which are seen on the film. While the novel does not specify where the campsite was located, exactly, later, Pottermore revealed it was in Dartmoor, which is actually landlocked.