Louisville is Kentucky's most populous city and county seat of Jefferson County. The city is located in north-central Kentucky on the Kentucky-Indiana border at the only natural obstacle in the Ohio River, the Falls of the Ohio. Louisville is most known as the home of "The Most Exciting Two Minutes in Sports": the Kentucky Derby, the widely watched first race of the Triple Crown of Thoroughbred Racing. The settlement that became the City of Louisville was established in 1778 by George Rogers Clark and is named after King Louis XVI of France.

The first European settlement made in the vicinity of current day Louisville was on Corn Island in 1778 by Col. George Rogers Clark. Today, Clark is recognized as the founder of Louisville, and several landmarks are named after him.

Two years later, in 1780, the Virginia General Assembly approved the town charter of Louisville. The city was named in honor of King Louis XVI of France, whose soldiers were aiding Americans in the Revolutionary War. In 1803, explorers Meriwether Lewis and George Rogers Clark's younger brother William Clark planned their expedition across America in the original town of Clarksville, Indiana at the present day Falls of the Ohio in Louisville.

Louisville was a crucial point for many enslaved blacks since Kentucky, a border state in the Civil War, was nevertheless a slave state and crossing the Ohio River could lead to freedom in the North. Its significant black population and location on the Ohio River resulted in it becoming a stop on the Underground Railroad.

The first Kentucky Derby took place on May 17, 1875, at the Louisville Jockey Club track (later renamed to Churchill Downs). The Derby was originally trumpeted by Meriwether Lewis Clark, Jr., the grandson of William Clark of the Lewis and Clark Expedition and grandnephew of the city's founder George Rogers Clark. Ten thousand spectators were present at the first Derby to watch Aristides win the race.

Recently, Louisville has emerged as a major hub for the health care and medical sciences industries. Louisville has been significant to advancements in heart and hand surgery as well as cancer treatment. Some of the earliest artificial heart transplants were conducted in Louisville. The city is also home to Humana, one of the nation's largest health insurance companies.