line house

{{Short description|Building deliberately built across a geopolitical boundary}}

File:The Haskell Free Library and Opera House in Derby Line, Vermont and Stanstead, Quebec.jpg is the best-known among buildings that straddle the Canada–United States border. The border is marked with boulders. In this picture, Canada is on the left side and the United States is on the right.]]

File:HaskellLibraryBorderLine.jpg

File:La-Cure-Douane.jpg in La Cure. The border runs lengthwise through the two buildings, passing just to the left of the mural. The mural and everything to the right of it lies in Switzerland, and France lies to the left.]]

File:2016 Views from the dome of Saint Peter's Basilica 16.jpg on the border between the Vatican City and Italy. The border runs crosswise through the building, with the Vatican City on the right side and Italy on the left side of the building.]]

File:Italia-SanMarino.JPG and San Marino in Dogana.]]

File:House Shared By Two Countries.jpg and the Netherlands in the towns of Baarle-Hertog and Baarle-Nassau respectively. Belgium is on the left marked with letter "B" on the pavement and the Netherlands is on the right marked with letter "NL" on the pavement.]]

A line house is a building deliberately located so that an international boundary passes through it.Farfan, Matthew (2009). The Vermont–Quebec Border: Life on the Line. Arcadia Publishing. {{ISBN|0738565148}}Joint Report upon the Survey and Demarcation of the Boundary between the United States and Canada from the Source of the St. Croix River to the St. Lawrence River, International Boundary Commission, 1924, pp. 36, 40, 60, 65, 73–4, 83, 107, 116, 341

One such building on the boundary between the United States and Canada is the Haskell Free Library and Opera House in Stanstead, Quebec, and Derby Line, Vermont. The border is marked on the floor in a reading room and an auditorium. A number of single-family residences and some industrial buildings straddle the boundary in those two towns.

The International Boundary Commission encourages line houses to be abandoned as part of its mandate to clearly demarcate the Canada–United States border. The Haskell Free Library and most other line houses are on the Collins–Valentine line between Quebec and New York/Vermont.{{Cite web |url=http://www.clui.org/section/united-divide-a-linear-portrait-usacanada-border-1 |title=Chapter 1: Northern Maine and New Hampshire |website=United Divide: A Linear Portrait of the USA/Canada Border |publisher=The Center for Land Use Interpretation |publication-date=Winter 2015}}

Line houses exist also in Baarle-Hertog and Baarle-Nassau on the border between Belgium and the Netherlands.

The border between the United Kingdom and the Republic of Ireland passes through many houses and other buildings.[https://www.belfastlive.co.uk/news/belfast-news/irish-border-photos-show-how-16677974 Irish border photos show how invisible line cuts through homes, a graveyard and roads]: Belfast Live, 4 August 2019

In Sungai Haji Kuning at Sebatik Island, which is divided between Malaysia and Indonesia, there is a house divided by the countries' borders.[https://worldofbuzz.com/this-house-built-on-the-middle-of-a-border-is-half-malaysian-and-half-indonesian/ This House Built On the Middle of a Border Is Half Malaysian and Half Indonesian!], World of Buzz

Paul VI Audience Hall, located partially in the Vatican City, but mostly in Rome, Italy: the Italian part of the building is treated as an extraterritorial area of the Holy See and is used by the Pope as an alternative to Saint Peter's Square when conducting his Wednesday morning General Audience.