It is a quadrifrons trumphal arch, surmounted by an unusual octagonal cupola,and was erected (entirely in marble) by Gaius Calpurnius Celsus, quinquennial duumvir of the city, to commemorate the victories of Lucius Verus, junior colleague and adoptive brother of the Emperor Marcus Aurelius, over the Parthians in the Roman–Parthian War of 161–66.
The War Memorial, a quadrifrons arch, was designed by Edwin Lutyens and built in 1923, to commemorate the dead of the First World War.