The year 1785 in architecture involved some significant architectural events and new buildings.

Events

• May 20 – The United States Land Ordinance of 1785 determines the layout of townships in the western territories.
• July 17 – A groundbreaking ceremony is held for the Pella Palace in Russia, designed by Ivan Starov; it will never be completed.^[1]

Buildings and structures

Buildings completed

• May 19 – Plaza de Toros de Ronda, Spain.
• September 7 – Notre-Dame de Guebwiller inaugurated.
• Attingham Park, Shropshire, England, designed by George Steuart.
• Chertsey Bridge over the River Thames in England, designed by James Paine and Kenton Couse.
• Marble Palace in Saint Petersburg, Russia, designed by Antonio Rinaldi.
• Church of St. Stephen Harding in Apátistvánfalva.
• Odigitrievsky Cathedral in Ulan Ude, Russia.^[2]
• Palace of Iturbide in Mexico City, designed by Francisco Antonio de Guerrero y Torres.
• Grand Palace, Bangkok, completed.
• Rebuilding of Babolovo Palace in Tsarskoe Selo, Russia, by Ilya Neyelov.
• Modifications to Neue Kirche, Berlin, by Georg Christian Unger after a design by Carl von Gontard.
• Mussenden Temple on the north coast of Ireland.

Births

• October 29 – Achille Leclère, French architect (died 1853)
• William Cubitt, English civil engineer (died 1861)

Deaths

• August 11 – Marie-Joseph Peyre, French architect (born 1730)
• September 26 – Ventura Rodríguez, Spanish architect and artist (born 1717)