The year 1766 in architecture involved some significant events.

• April 17 – James Craig's plan for the New Town, Edinburgh, Scotland, wins the prize offered by the city council in January.^[1]
• October 28 – Coldstream Bridge across the River Tweed on the England/Scotland border, designed by John Smeaton, is opened to traffic.
• Paxton House, Berwickshire, Scotland, is completed.
• Strawberry Hill House, London, designed by Horace Walpole, is completed in the Gothick style.
• Pazo de Raxoi in Santiago de Compostela, Spain, is completed.
• Rebuilding of Potocki Palace, Warsaw, to designs by Jakub Fontana, is completed.
• Shardeloes (country house) in Buckinghamshire, England, designed by Stiff Leadbetter, is completed.
• New main residence at Skjoldenæsholm Castle in Denmark, possibly designed by Philip de Lange, is built.
• Theatre Royal, Bristol, England, built by Thomas Paty to designs by James Saunders, is opened.
• New Drottningholm Palace Theatre in Stockholm, designed by Carl Fredrik Adelcrantz, is completed as an opera house.
• St. Paul's Chapel on Broadway (Manhattan) in New York City, designed by Thomas McBean, is completed.
• St Nikolaus church at Brohl in the Rhineland, designed by J. A. Neurohr, is built.
• St Markus church at Pünderich in the Rhineland, designed by Paul Stähling, is built.
• Stone Hermitage and Rozhdestvensky Bridges in Saint Petersburg are completed.

• John Gwynn – London and Westminster Improved

• August 3 – Jeffry Wyatville, English architect (died 1840)

• January 19 – Giovanni Niccolò Servandoni, French architect and painter (born 1695)
• May 6 – Johann Michael Fischer, German architect (born 1692)
• July 14 – František Maxmilián Kaňka, Czech architect (born 1674)
• August 18 – Stiff Leadbetter, English architect (born c.1705)
• November 16 – Dominikus Zimmermann, German rococo architect (born 1685)
• December 20 – Giorgio Massari, Venetian baroque architect (born 1687)
• Isaac Ware, English architect (born 1704)