Gibbs surround

[2] Some definitions extend to including arches or square openings merely with alternate blocked elements that continue round the top in the same manner as the sides, as in the rectangular windows of the White House's north front basement level.

A version with columns rather than a moulded architrave was illustrated by Sebastiano Serlio in 1537, where the voussoirs but not the keystone push up past the bottom edge of the pediment.

Variations of this style are seen, for example, in the upper-floor windows of Palazzo Thiene in Vicenza (apparently part of the additions by Palladio), where only the keystone breaks into the pediment.

[1] The effect of a Gibbs surround is achieved round the doors of the south front of the Petit Trianon by stopping the horizontally banded rustication short in alternate levels.

Early examples in America, derived from the many English pattern-books used there, include the Aquia Church in Virginia of the 1750s and St. Paul's Chapel in Manhattan, completed in 1766.