(From: http://www.visual-arts-cork.com/painting/quadratura.htm)
"Quadrature Illusionism is mainly associated with
Italian church fresco painting, notably that of the Baroque era.
A particularly inspiring form of Christian art - and a key feature
of Catholic Counter-Reformation Art (c.1560-1700) - this pure type of quadratura relies heavily on 17th-century theories of linear perspective but produces a more complete form uniting
architecture, painting and sculpture."
From: http://www.visual-arts-cork.com/