 The arch of a lancet opening is often equilateral, but sometimes is much more acute, and when employed in the arcade of a choir apse, such as at Westminster Abbey, adds to the emphasis of height.The simple shape of the lancet arch may appear in Early Gothic buildings on openings of all types, doorways, niches, arcades, including galleries; and belfry openings.The use of lancet windows is found in the Early Gothic architecture of France, at Saint-Denis, and Sens and Senlis cathedrals.