features an oval, glass-paned oculus skylight at roof level atop the three-story galleried staircase with turned mahogany bannisters. This stairwell originally rose open from the cellar to the servants' quarters, now the attic, but was partitioned when the house was divided into north and south duplex units after the van Rensselaer family first sold it in 1865. Later, central heating replaced the use of 8 faux-grained black marble fireplaces and the two kitchen hearths in the cellar. The duplex layout consists of the north half containing the center hall, and the south using the side (Central Avenue) entrance and a perpendicular simple mahogany bannister servants' staircase to access the three floors and cellar. The north, rear, first floor (dining) room features a pair of built-in corner closets with concave-curved doors; the front (living) and back (dining) rooms are divided by sliding pocket doors. All interior doors are grain-painted mahogany and feature original brass hardware, stamped "A. Wollensak, Albany." All rooms feature heavy plaster moulding at the 14' ceilings and deep wood-paneled trim and folding casement shutters at all windows. The formal first-floor rooms now have grain-painted floors, but were originally covered with tan, red and black over-plaid ingrained wool carpet, a swatch of which survives. The ground floor is lined with a course of bricks between the sub-flooring and finished, plastered cellar ceiling providing insulation and fire resistance from the kitchen areas below. The exterior walls are constructed in an envelope fashion with an air space between the heavy brick exterior and the heavy plaster interior walls. This air space "breathed" through warm or cool air circulation from the cellar upwards and across the rafters and exited out the oculus cupola windows atop the roof. The cupola was lost during the Hurricane of 1938, which also precipitated a water-borne collapse of a section of the north end of the east cellar wall. The adjacent (north) Patroon Agent's Office, separated from the house property in 1865, has an elaborate set of heavy cast-iron security features, including doors, interior window shutters, iron bars and drop-down panels at the interior windows of what was likely a vault. An open cistern area in the main office floor has now been covered over to provide floor space in the large, elegant vaulted-ceiling room. This area was rehabilitated and decorated as offices in the early 1990s for a prominent general contractor, Henry V. Rector and is