The year 1804 in architecture involved some significant events.

Buildings and structures

Buildings

• May 21 – Père Lachaise Cemetery in Paris, laid out by Alexandre-Théodore Brongniart, is opened.^[1]
• August 28 – Cathedral of the Holy Trinity (Quebec), designed by Major William Robe and Captain William Hall, is consecrated.^[2]
• The Government House in the Bahamas is completed.
• Montevideo Metropolitan Cathedral in Uruguay is consecrated.
• Dalongdong Baoan Temple in Taipei, Taiwan, is completed.
• The Pont des Arts in Paris, designed by Louis-Alexandre de Cessart and Jacques Dillon, is completed.
• Rostokino Aqueduct for Moscow water supply is completed by Colonel Ivan Gerard to the designs of Friedrich Wilhelm Bauer.

Awards

• Grand Prix de Rome, architecture: Jules Lesueur.

Births

• February 7 – William Tinsley, Irish architect working in the United States (died 1885)
• March 1 – John Henderson, Scottish ecclesiastical architect (died 1862)
• March 13 – Thomas Allom, English architect (died 1872)
• September 4 – Thomas Ustick Walter, American architect (died 1887)
• November 3 – Alexander Dick Gough, English architect (died 1871)
• December 19 – George Townsend Andrews, English architect known for railway stations in Yorkshire (died 1855)
• John S. Norris, American architect (died 1876)

Deaths

• March 18 – Louis Jean Desprez, French painter and architect working in Sweden (born 1743)
• Nicholas Revett, English amateur architect (born 1720)