The year 1851 in architecture involved some significant architectural events and new buildings.

Events

• Missions Héliographiques established by Prosper Mérimée to photograph historical French architecture.

Buildings and structures

Buildings opened

• February 5 – Saint Thomas Episcopal Church and Rectory, Smithfield, Rhode Island, USA, designed by Thomas Alexander Tefft.^[1]
• May 1
  • The Crystal Palace, home of the Great Exhibition, erected in Hyde Park, London to the design of Joseph Paxton.
  • Permanent Windsor Riverside railway station in England completed to the design of William Tite.
• May 31 – Madonna dell'Archetto, Rome Italy.^[2]
• July 25 – Holy Trinity Church, Bangalore, India.^[3]
• October 1 – Alabama State Capitol, Montgomery, Alabama.

Buildings completed

• Osborne House on the Isle of Wight, England, designed by Prince Albert in consultation with builder Thomas Cubitt.^[4]
• Dock Tower in Grimsby, England.
• Donaldson's Hospital in Edinburgh, Scotland, designed by William Henry Playfair.
• De Wachter, Zuidlaren, Netherlands.
• Wat San Chao Chet, Bangkok, Thailand.
• Stone Bastei Bridge, Saxony.

Buildings commenced

• St. Stephen's Basilica in Budapest, Hungary, designed by Miklós Ybl.
• Muhammad Amin Khan Madrasa in Khiva, Uzbekistan.
• Hurstpierpoint College in England, designed by Richard Cromwell Carpenter.

Publications

• Gottfried Semper – The Four Elements of Architecture, part 1
• Edmund Sharpe – The Seven Periods of English Architecture.

Awards

• RIBA Royal Gold Medal – Thomas Leverton Donaldson.
• Grand Prix de Rome, architecture – Gabriel-Auguste Ancelet.

Births

• March 10 – Heinrich Wenck, Danish architect (died 1936)
• March 26 – John Eisenmann, Cleveland-based US architect (died 1924)
• June 29 – (Edmund) Peter Paul Pugin, English architect, son of Augustus Welby Pugin and half-brother of Edward Welby Pugin (died 1904)^[5]

Deaths

• October 13 – Samuel Beazley, British theatre architect and writer (born 1786)^[6]
• October 25 – Giorgio Pullicino, Maltese painter and architect (born 1779)
• November 18 – Jacob Ephraim Polzin, German Neoclassical architect (born 1778)