Cheapside is a famous street in London, England, known for its commercial heritage and central role in the city's development from medieval times to the present day.

The name "Cheapside" means "alongside the market," with "cheap" being an archaic word for "market," from Old English ceapan, "to buy." It is thus different from yet etymologically related to the modern English word cheap, meaning "inexpensive," which was originally a shortening of good ceap, a "good buy."

In medieval times the road was one of two main markets in London, and was originally known as Westcheap, as opposed to its counterpart known as Eastcheap. It was originally one London's principal produce markets, which is why many adjoining streets to this day have names like Honey Lane, Milk Street, Bread Street, and Poultry, but clothing, hard goods, and luxury items were also sold.

Entering into the early modern era, Cheapside remained a vibrant commercial hub, but was also known as a site for significant public events, including jousting tournaments, public executions, royal pageants, and royal processions.

In 1666, Cheapside was devastated by the Great Fire of London, which led to significant rebuilding and redesign. Post-fire reconstruction saw the introduction of wider streets and more fire-resistant buildings, creating the modern landscape of Cheapside which perdures to the present day.

The most famous building on Cheapside is St. Mary le Bow Church, originally constructed in 1080, with the current building dating to 1680. The church is famous for its "Bow Bells," with only those born within earshot of the bells being considered a true Cockney.

Cheapside is also an iconic location in English literature, including references by the likes of William Shakespeare, Jane Austen, and Charles Dickens.

Today Cheapside is located within the pricy and prestigious "City of London," which is the commercial and financial heart of the United Kingdom, and is now home to large department stores, upscale boutiques, and luxury fashion houses. It thus remains an important part of the economic and cultural fabric of both the city and the nation.