In 1967 Frank Stella began a series of brightly colored paintings based on the protractor, a drafting tool used for measuring and constructing angles. With the protractor he made three semicircular designs--the "interlace," the "rainbow" (seen here), and the "fan"--which he calls variations I, II, and III. He used these designs as the basis for the many paintings in the Protractor series.Stella named the paintings after circular cities and archaeological sites in the Middle East, where he had traveled in 1963. Tahkt-i-Sulayman is an ancient shrine in Azerbaijan, Iran. But Stella insists that the meaning of his work is purely formal: "My painting is based on the fact that only what can be seen there is there. It really is an object.... You can see the whole idea without any confusion. What you see is what you see."