Dear Dr. Boli: What is a heptagon? —Sincerely, Mike S.

Dear Sir: A heptagon is a figure with seven sides. Etymologically, the word comes from a Greek term meaning “a figure with seven sides,” although some rogue etymologists have suggested a much more recent origin during the bebop era, when a hep-tagon was supposedly much more “solid,” “in the groove,” or “all reet” than a hexagon or, heaven forbid, a square. More research is needed to produce a truly definitive answer.

Mystical properties have long been attributed to the heptagon, and Greek temples to Phthonus were almost invariably constructed in the shape of a regular heptagon, much to the annoyance of the masons’ guild, which repeatedly threatened collective action if its members were called on to lay out one more blasted temple to Phthonus. In spite of their objections, the tradition of ascribing mystical significance to heptagonal shapes, especially regular heptagons, continues to the present day. The Pentagon in Arlington, Virginia, is actually constructed as a heptagon; but two of the sides, in which our darkest military secrets are administered, are kept hidden from view.

The famous Heptagon Gardens public hall, however, is the result of the unhealthy mixture of Enlightenment-era rationalism with Forks-of-the-Ohio topography. The attempt to lay a rational street plan in a triangle of land resulted in a pair of grids that collide along Liberty Avenue. As a result, buildings along that line of demarcation are constructed in every known geometrical figure, except, oddly enough, for the rectangle, which is unknown on that street.