is a city in Madison and Limestone Counties in the U.S. state of Alabama, and the county seat of Madison County. Huntsville includes the biggest space museum in the world. It is the largest city in northern Alabama in a region of a half-million people, with the city proper having 171,327 residents (2007 estimate). Started with a single cabin in 1805, the city was incorporated six years later as Twickenham. However, it was renamed "Huntsville" (after first settler John Hunt) during the War of 1812, and it has grown across nearby hills and along the Tennessee River, adding textile mills, then munitions factories, to become a major city, hosting the NASA Marshall Space Flight Center and Redstone Arsenal.
As of the 2000 census, the population of Huntsville was 158,216. In 2008, the estimated population of the Huntsville Metropolitan Area was 395,645, with the city proper (in 2007) having 171,327 residents. Huntsville is the largest city in the four-county Huntsville-Decatur Combined Statistical Area, which in 2008 had a total population of 545,770.
Huntsville is located at 34°42' North, 86°35' West (34.7, -86.6). According to the Huntsville Times from Tuesday April 15, 2008, the city now has a total area of 202 square miles (451.8 km²). Recent annexations into Limestone County have pushed Huntsville City limits to a total of 9 miles inside Limestone County going to I-65 in spots and borders Athens and Decatur.
Huntsville is located in the Tennessee River Valley. Several plateaus and large hills partially surround the city. These plateaus are associated with the Cumberland Plateau, and are locally called "mountains". Monte Sano Mountain (Italian for "Healthy Mount") is the most notable, and is east of the city along with Round Top (Burritt), Chapman, Huntsville, and Green Mountains. Others are Wade Mountain to the north, Rainbow Mountain to the west, and Weeden and Madkin Mountains on Redstone Arsenal in the south. Brindlee Mountain is visible in the south across the Tennessee River.
As with other areas along the Cumberland Plateau, the land around Huntsville is karst in nature. The city was founded around the Big Spring, which is a typical karst spring, and many caves perforate the limestone bedrock underneath the surface, as is common in karst areas. The headquarters of the National Speleological Society are located in Huntsville.