The year 1821 in architecture involved some significant events.

Buildings and structures

Buildings

Karl Friedrich Schinkel's design for the Schauspielhaus Berlin

• The Schauspielhaus in Berlin (begun in 1819), designed by Karl Friedrich Schinkel, is completed.
• The Palais Leuchtenberg in Munich (begun in 1817), designed by Leo von Klenze, is completed.
• The Haymarket Theatre in London, designed by John Nash, is completed.
• Prince Ludwig I of Bavaria, wishing to build a monument to German unity and heroism (and the defeat of Napoleon), commissions Leo von Klenze to build a replica of the Parthenon on a bluff overlooking the Danube River near Regensburg, the Walhalla memorial.
• The Strasbourg Opera House is completed
• The Maitland Monument in Corfu, designed by George Whitmore, is built.

Awards

• Grand Prix de Rome, architecture: Guillaume-Abel Blouet

Births

• January 2 – Napoleon LeBrun, American architect (died 1901)
• February 4 – Major Rohde Hawkins, English school and church architect (died 1884)
• February 13 – John Turtle Wood, English architect (died 1890)
• February 20 – Frigyes Feszl, Hungarian architect (died 1884)
• April – Thomas Brunner, English-born architect working in New Zealand (died 1874)

John Rennie the Elder

• April 11 – James Campbell Walker, Scottish architect (died 1888)
• July 4 – A. J. Humbert, English architect patronised by the royal family (died 1877)
• August 1 – James Gowans, Scottish architect (died 1890)
• November 26 – Charles Webb, English-born architect working in Victoria (Australia) (died 1898)
• Giuseppe Bonavia, Maltese architect (died 1885)
• John Elkington Gill, English architect working in Bath (died 1874)

Deaths

• March 1 – John Yenn, English architect (born 1750)
• October 4 – John Rennie the Elder, Scottish-born civil engineer (born 1761)