In architecture, a Long gallery is a long, narrow room, often with a high ceiling. In Britain, long galleries were popular in Elizabethan and Jacobean houses. They were often located on the upper floor of the great houses of the time, and stretched across the entire frontage of the building. They served several purposes: among others, they were used for entertaining guests, for taking exercise in the form of walking when the weather was inclement, and for displaying art collections.
A long gallery has the appearance of a spacious corridor, but it was designed as a room to be used in its own right, not as a means of passing from one room to another. In the 16th century, the seemingly obvious concept of the corridor had not been introduced to British domestic architecture: rooms were entered from outside, or by passing from one room to another.
Later long galleries were built in Victorian houses such as Nottingham Castle.
Notable long galleries in the UK can be seen at:
- Apethorpe Hall Conservation by English Heritage under way
- Aston Hall
- Blickling Hall
- Burghley House
- Broughton Castle 
- Burton Agnes Hall 
- Burton Constable Hall 
- Haddon Hall 
- Ham House, compact and running from front to rear.
- Hardwick Hall, one of the largest.
- Hatfield House 
- Little Moreton Hall
- Longleat House (The long gallery is now called the Saloon)
- Montacute House 
- Osterley Park 
- Scone Palace 
- Syon House 
- Temple Newsam House  (Jacobean long gallery, later modified and now called the "Picture Gallery")
- The 'Long Gallery': Its Origins, Development, Use and Decoration by Rosalys Coope in Architectural History, Vol. 29, 1986 (1986), pp. 43–72+74-84
- "Gallery". Encyclopædia Britannica (11th ed.). 1911.