The beauty of Charleston can offer a challenge to the eye of the beholder in some of the city’s most historic landmarks. A number of the grand facades on the peninsula, such as the 1825 portico at South Carolina Society Hall, feature an ancient architectural illusion called entasis.
This barely-noticeable feature entails a tapering decrease in circumference of portico columns at from bottom to top. It was first used by ancient Greeks to on their towering temples to compensate for a linear distance in perception that naturally tricks the eye. If columns are the same breadth all the way up, the width ratio appears concave from eye-level, and the solution is to reverse the image by making the column convex.
The word entasis comes from Greek, meaning “to stretch tight”. The concept was perpetrated in the designs of Andrea Palladio, whose work inspired the Classic, Roman and Greek architecture that is evident throughout Charleston today. Even the Rolls Royce company got in the entasis act by the 20th century, adding the illusion to grills on the front of its cars to give the frame a more substantial look.
Most of the larger columns on Charleston’s historic buildings are made of brick, and covered with stucco, offering bricklayers a challenge in building courses and bonding with a taper that nevertheless had to hold up massive pediments. Several, such as the columns of Hibernian Hall, had to be rebuilt after the earthquake of 1886.
Entasis is not the only optical illusion in Charleston’s columns. The intentional pitch in side porch “piazzas” that allows water to run off also creates the illusion that many houses are leaning. A great example is the 18th century house at 17 Meeting Street at the corner of Lamboll East. The high, narrow single-house style also features a three-story piazza, and the combination of pitched floors and narrow height makes the house look as if it is leaning to the North.