The front porch light is on, and a light beckons in an upstairs window. Yet Donna Dennis's 1983 Skowhegan Stairway—a covered stairway detached from a house, a large, self-contained, freestanding bit of sculpture-cum-architecture—is not altogether a friendly place. It resembles a building compressed into a narrow suggestion of itself, a sliver of a building. The front door's open window reveals, through lace curtains, a bleakly lit hall, a sign of absence—everyone is asleep, or gone, except the (unseen) occupant of that upstairs chamber.