The year 1799 in architecture involved some significant events.

• May 9 – St. Mark's Church in-the-Bowery in New York City, built by John McComb, Jr., is consecrated.
• Gracie Mansion in New York City, designed by John McComb, Jr., is built.
• The Chester Shot Tower, a grade-II*-listed shot tower, is built in the Boughton district of Chester, England.
• In New Orleans, The Cabildo (first phase) is completed (begun in 1795).
• Reconstruction of Town Hall, Vilnius, by Laurynas Gucevičius is completed.
• Broadway Tower, Worcestershire, England, designed by James Wyatt, is completed.^[1]
• Grand Pump Room, Bath, England, designed by Thomas Baldwin and John Palmer, is completed
• Hjo Church in Sweden is completed.

• Approximate date – William Thomas, English-born architect working in Canada (died 1860)

• February 6 – Étienne-Louis Boullée, French neoclassical architect (born 1728)
• April 17 – Richard Jupp, English architect (born 1728)
• June 11 – Joaquín Toesca, Italian-born architect working in Chile (born 1745)
• August 31 – Nicolas-Henri Jardin, French neoclassical architect (born 1720)