The exterior of the Memorial echoes a classic Greek temple and features Yule marble from Colorado. The structure measures 189.7 by 118.5 feet (57.8 by 36.1 m) and is 99 feet (30 m) tall. It is surrounded by a peristyle of 36 fluted Doric columns, one for each of the 36 states in the Union at the time of Lincoln's death, and two columns in-antis at the entrance behind the colonnade. The columns stand 44 feet (13 m) tall with a base diameter of 7.5 feet (2.3 m). Each column is built from 12 drums including the capital. The columns, like the exterior walls and façades, are inclined slightly toward the building's interior. This is to compensate for perspective distortions which would otherwise make the memorial appear to bulge out at the top when compared with the bottom, a common feature of Ancient Greek architecture.

Above the colonnade, inscribed on the frieze, are the names of the 36 states in the Union at the time of Lincoln's death and the dates in which they entered the Union. Their names are separated by double wreath medallions in bas-relief. The cornice is composed of a carved scroll regularly interspersed with projecting lions' heads and ornamented with palmetto cresting along the upper edge. Above this on the attic frieze are inscribed the names of the 48 states present at the time of the Memorial's dedication. A bit higher is a garland joined by ribbons and palm leaves, supported by the wings of eagles. All ornamentation on the friezes and cornices was done by Ernest C. Bairstow.

http://en.wikipedia.org/wiki/Lincoln_Memorial