Out and About: What is a triplex?

You decide: Is this a triplex?

It troubled me the last time this unit went on the market, nearly two years ago.  And it bothered me when I saw it again a few weeks ago.

The co-op was listed for $660,000 in October and now is at $589,000, after three reductions, with maintenance of $1,022.  In an 1886 brownstone in a low 80s Central Park block, it is said to contain one bedroom and one and a half baths.

There are exposed brick walls, a wood-burning fireplace, a spiral staircase and three windows described as “grand.”  (They are, actually.)