Denver, officially the City and County of Denver, is the capital and most populous municipality of the U.S. state of Colorado. Denver is in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains. The Denver downtown district is immediately east of the confluence of Cherry Creek with the South Platte River, approximately 12 mi (19 km) east of the foothills of the Rocky Mountains. Denver is nicknamed the Mile High City because its official elevation is exactly one mile (5280 feet or 1609.3 meters) above sea level, making it the highest major city in the United States. The 105th meridian west of Greenwich, the longitudinal reference for the Mountain Time Zone, passes directly through Denver Union Station.

Denver is ranked as a Beta- world city by the Globalization and World Cities Research Network. With an estimated population of 704,621 in 2017, Denver is the 19th-most populous U.S. city, and with a 17.41% increase since the 2010 United States Census, it has been one of the fastest-growing major cities in the United States. The 10-county Denver-Aurora-Lakewood, CO Metropolitan Statistical Area had an estimated 2017 population of 2,888,227 and is the 19th most populous U.S. metropolitan statistical area. The 12-city Denver-Aurora, CO Combined Statistical Area had an estimated 2016 population of 3,470,235 and is the 16th most populous U.S. metropolitan area. Denver is the most populous city of the 18-county Front Range Urban Corridor, an oblong urban region stretching across two states with an estimated 2016 population of 4,833,260. Denver is the most populous city within a 500-mile (800 km) radius and the second-most populous city in the Mountain West after Phoenix, Arizona. In 2016, Denver was named the best place to live in the United States by U.S. News & World Report.

The character of the neighborhoods varies significantly from one to another and includes everything from large skyscrapers to houses from the late 19th century to modern, suburban-style developments. Generally, the neighborhoods closest to the city center are denser, older and contain more brick building material. Many neighborhoods away from the city center were developed after World War II, and are built with more modern materials and style. Some of the neighborhoods even farther from the city center, or recently redeveloped parcels anywhere in the city, have either very suburban characteristics or are new urbanist developments that attempt to recreate the feel of older neighborhoods. Most neighborhoods contain parks or other features that are the focal point of the neighborhood.

Denver does not have larger area designations, unlike the City of Chicago, which has larger areas that house the neighborhoods (IE: Northwest Side). Denver residents use the terms "north", "south", "east", and "west".

Denver also has a number of neighborhoods not reflected in the administrative boundaries. These neighborhoods may reflect the way people in an area identify themselves or they might reflect how others, such as real estate developers, have defined those areas. Well-known non-administrative neighborhoods include the historic and trendy LoDo (short for "Lower Downtown"), part of the city's Union Station neighborhood; Uptown, straddling North Capitol Hill and City Park West; Curtis Park, part of the Five Points neighborhood; Alamo Placita, the northern part of the Speer neighborhood; Park Hill, a successful example of intentional racial integration; and Golden Triangle, in the Civic Center.