Maison carrée d'Arlac, Neoclassical folly in Mérignac, France.

The Maison carrée d'Arlac is a neoclassical folly in Mérignac, built 1785–1789 to plans by Jean-Baptiste Dufart. Its pale yellow stone front has a curved portico of six columns with plain capitals, above a broad flight of steps. The south facade carries a semi-circular Corinthian colonnade; inside, a two-storey rotunda salon is covered by a painted dome and ringed by a gallery for musicians.

Samuel Charles Peixotto, a Portuguese Jewish banker whose name was Gallicised to Peychotte, bought the Arlac estate in 1768 and had this house built between 1785 and 1789 to plans by Jean-Baptiste Dufart. After his near-ruin and death in 1805, the Rodrigues-Henriquez family bought it at auction in 1810. Élie Gintrac, director of the Bordeaux medical school, made it his summer residence from 1827 and bred silkworms on mulberry trees there. Madame Goudal ran a military hospital in it during the First World War, German forces occupied it from 1940 to 1944, and Mérignac bought it for one symbolic franc in 1990.

Locals nicknamed it the "Maison carrée" for its square plan, and the name stuck alongside Peychotte, the francised form of banker Samuel Charles Peixotto's surname. The upper floor is reached by a hidden staircase tucked into the junction between the round salon and the rectangular vestibule, and a circular gallery above the rotunda was meant for musicians playing during gatherings below.

The building stands on a hill in Mérignac, just outside Bordeaux, and is not open for regular visits while it awaits conversion into a Maison des arts planned for early 2027. The monumental convex stone steps and the surrounding park can be seen from the public street; the landscaped grounds have been much reduced by later housing development.

The house is said to have inspired the model for the Château de Rastignac in Dordogne and for the White House in Washington. The circular gallery above the rotunda was built to seat musicians playing for guests below, reached by a service stair tucked into the junction between the round salon and the rectangular vestibule.