Locust Street is a major historic street in Center City Philadelphia. The street is the location of several prominent Philadelphia-based buildings, historic sights, and high-rise residential locations. It is an east–west street throughout Center City Philadelphia and runs largely parallel to Chestnut Street, another major Center City Philadelphia street.

Locust Street is one of several Philadelphia streets bordering Rittenhouse Square, one of the five original parks established by the city's founder, William Penn, in the late 17th century.

In 1682, Locust Street was one of the streets laid out by surveyor Thomas Holme in William Penn's original plan of the city.

In the 1830s, some of Locust Street, around 13th Street, in Center City Philadelphia, was purchased by John Hare Powel, a Pennsylvania politician and agriculturist.

The street includes notable buildings designed by some of the most preeminent architects of the Gilded Age, including a Horace Trumbauer-designed Beaux-Arts limestone building at 1629 Locust Street, a Georgian Revival set of buildings designed by Cope and Stewardson at 1631 and 1633 Locust Streets, a Frank Miles Day-designed Medieval mansion at 17th and Locust Streets, and several John Notman-designed houses and St. Mark’s Church on the 1600 block of Locust Street.

Locust Street is now a hybrid of commercial and residential buildings. It historically was exclusively a residential street with mansions and home to many of the city's most affluent residents.

Notable residents of Locust Street have included author and poet Edgar Allan Poe and Union army general Robert Patterson.

Between 1838 and 1844, the famed author and poet Edgar Allan Poe lived at four different locations in Philadelphia, including one residence at 16th and Locust Streets. While in Philadelphia, Poe authored 31 stories, including "The Murders in the Rue Morgue" in 1841 and "The Gold-Bug" and "The Tell-Tale Heart", both in 1843.