The Wellington Arch, also known as the Constitution Arch or (originally) as the Green Park Arch, is a Grade I-listed triumphal arch by Decimus Burton that forms a centrepiece of Hyde Park Corner in central London, between the corner where Hyde Park meets Green Park. The Arch stands on a large green-space traffic island with crossings for pedestrian access. From its construction (1826–1830) the arch stood in a nearby location, slightly to the east, directly across from Burton's Ionic screen entrance to Hyde Park; it was moved a short distance to its current site at the top of the Constitution Hill road in 1882–1883. The triumphal arch originally supported a colossal equestrian statue of the 1st Duke of Wellington by the sculptor Matthew Cotes Wyatt, acquiring its name as a result. Peace descending on the Quadriga of War by sculptor Adrian Jones, a bronze of the Goddess of Victory Nike riding a quadriga, has surmounted the arch since 1912.

A triumphal arch is a free-standing monumental structure in the shape of an archway with one or more arched passageways, often designed to span a road, and usually standing alone, unconnected to other buildings. In its simplest form, a triumphal arch consists of two massive piers connected by an arch, typically crowned with a flat entablature or attic on which a statue might be mounted or which bears commemorative inscriptions. The main structure is often decorated with carvings, sculpted reliefs, and dedications. More elaborate triumphal arches may have multiple archways, or in a tetrapylon, passages leading in four directions.