Giacomo Leoni (1686 – 8 June 1746), also known as James Leoni, was an Italian architect, born in Venice. He was a devotee of the work of Florentine Renaissance architect Leon Battista Alberti, who had also been an inspiration for Andrea Palladio. Leoni thus served as a prominent exponent of Palladianism in English architecture, beginning in earnest around 1720. Also loosely referred to as Georgian, this style is rooted in Italian Renaissance architecture.
Having previously worked in Düsseldorf, Leoni arrived in England, where he was to make his name, in 1714, aged 28. His fresh, uncluttered designs, with just a hint of baroque flamboyance, brought him to the attention of prominent patrons of the arts.