The City of Thornton is located just north of Denver, and is the sixth largest city in Colorado.The City of Thornton is a great place to live, work, grow and play. Thornton is a diverse community with a strong commitment to quality of life and environmental issues. The city's location also provides an excellent environment for cultural, recreational, and outdoor enthusiasts. Thornton has aggressively pursued recreation programs with nearly 1,000 acres of land developed or designated for public parks. The numerous lighted tennis courts, athletic fields, indoor and outdoor swimming pools, recreation centers and gymnasiums offer recreation opportunities for people of all ages and activity levels. Our location provides an ideal environment for business, recreation, and residences.