Travel TipsChicago. the third-largest city in the United States, located in the state of Illinois. It is known for its architecture, museums, parks and vibrant cultural scene. The city has a rich history, having been founded in 1830, and serving as a major transportation hub and center of industry. Chicago’s culture, history and architecture, makes it the popular city it is today. Please enjoy this chicago travel guide, with the best tips and to do’s.