The thriving town of Horsham may look modern, but it dates back to at least the 10th century. For many years it shared the county assizes with Lewes and Chichester. The parish church of St Mary dates to the 12th century, and stands at one end of a long street known as The Causeway, lined with attractive old houses.
One of the most famous residents of Horsham is the poet Percy Bysshe Shelley, whose monument can be found in the church. Nearby is Causeway House, an historic 16th century half-timbered building which serves as the home of Horsham Museum. Near Horsham is Christ's Hospital School, a Bluecoat school for boys founded by Edward VI in 1552. It was moved from London to Horsham in 1902.

Just outside the town is Warnham Nature Reserve, a popular area for bird-watching.