From Longman Dictionary of Contemporary Englishbuilt-upˌbuilt-ˈup adjective a built-up area has a lot of buildings and not many open spaces He was fined for speeding in a built-up area.
Examples from the Corpus
built-up• Try to see five miles ahead on a country road and at least two to three hundred yards in a built-up area.• In built-up areas, the problem is cars and street lights.• On passage, and sometimes in winter, Water Rails may occur in built-up areas.• Under normal circumstances barred owls do not frequent built-up areas.• It gathered speed and raced towards the built-up complexes.• He tugs one leg up and examines the built-up shoe.• The closed, trusting eyes were surrounded by scars and small mounds of built-up skin.• She garnished her built-up Trifle with strips of bright currant jelly, crystallised sweetmeats or flowers. 