The year 1791 in architecture involved some significant architectural events and new buildings.

Events

• The elevations of Charlotte Square in Edinburgh, Scotland, are designed by Robert Adam.
• Polish architect Jakub Kubicki is ennobled.

Buildings and structures

Buildings opened

• January 6 – Théâtre Feydeau, Paris, designed by Jacques Legrand and Jacques Molinos.
• November 7 – The Custom House, Dublin, Ireland, designed by James Gandon.

Buildings completed

• Bara Imambara, Lucknow, India
• Brandenburg Gate, Berlin, Germany
• Clyne Castle, Swansea, Wales, built by Richard Phillips
• Gammel Køgegård, Køge, Denmark (main house)^[1]
• Buenos Aires Metropolitan Cathedral, Argentina (rebuilt)
• Plaza Mayor, Madrid, remodelling by Juan de Villanueva
• Rock Castle (Hendersonville, Tennessee), United States, home of Daniel Smith.^[2]
• Tower of Hercules (lighthouse) in Spain (remodelling)
• Dar Hassan Pacha (palace) in the Casbah of Algiers.^[3]

Births

• January 14 – Thomas Oliver, English neoclassical architect (died 1857)^[4]
• March 15 – Lewis Vulliamy, English architect (died 1871)
• April 17 (bapt.) – William Cubitt, English building and civil engineering contractor and politician (died 1863)
• June 7 – Giacomo Moraglia, Milanese neoclassical architect (died 1860)

Deaths

• December 19 – Jean-François de Neufforge, Flemish architect and engraver (born 1714)^[5]