Marchese Luigi Cagnola (* 9 June 1762 in Milan; 14 August 1833 in Inverigo) was an Italian architect.
Cagnola attended the Clementine College in Rome and the University of Pavia. Actually, he was destined for the legal profession and initially worked for the Austrian administration in Milan, but ultimately opted for architecture. His project for the Porta orientale (later Porta Venezia) in Milan was praised, but not realised for cost reasons. Cagnola's provisional wooden triumphal arch on the occasion of the wedding of Eugène Beauharnais to Princess Auguste Amalia of Bavaria in 1806 was so popular that it was decided to make it in marble. The result is today's Arco della Pace. The Outer Castle Gate in Vienna was also built in 1821-1824 by Peter Nobile according to plans by Luigi Cagnola by soldiers of the Austrian army. Cagnola also designed the Milan Porta Ticinese, called Porta di Marengo in Napoleonic times, and the Campanile of Urgnano.