ambulatory, and apse The chancel is directly north of the nave, slightly raised above it and separated from the nave by a limestone railing with 20 quatrefoil medallions. The western portion of the rail contains a pulpit with a wooden canopy and three carved limestone blocks. A labyrinth composed of three types of marble; it was inspired by a similar design at Chartres Cathedral and is inlaid in the middle of the chancel floor. The labyrinth is flanked on both sides are four rows of oaken choir stalls with carvings of Psalms texts. To the north, behind the choir stalls, is the organ console. A communion table made of Caen stone is near the back of the chancel in the center, behind which is a baptismal pool. The back of the chancel contains a convex polygonal wall that includes seven bays, each with three vertical tiers that are a few feet above the corresponding tiers in the nave. The lowest tier contains pointed arches with an elaborate stone chancel screen; the middle tier contains cusped arches with colonettes; and the top tier serves as the clerestory. Each of the three center bays behind the chancel screen has one window group on the lower tier, each of which has two lancet windows topped by a rose window and is divided by vertical buttresses. The apse clerestory, the upper section of the ambulatory, is recessed slightly inward. The upper section's fenestration is similar in form; each window grouping contains a rose window above a pair of lancet windows but the window groupings are on five sides of the polygon. The vertical piers of the chancel wall converge above the clerestory level, creating an apse above the chancel and ambulatory. Narthex The narthex, which was designed in the late Gothic style with a Romanesque layout, is directly south of the nave and can be accessed from the church's West Portal. The narthex is split into four vaults that have Guastavino tiled ceilings that are supported by simple limestone columns. A stone spiral staircase on the west side of the narthex, directly south of the West Portal, leads to the basement. There are two grisaille windows and one rose window on each of the western and eastern sides of the narthex. The eastern wall has four 16th-century lancet windows that were previously in the Park Avenue Baptist Church; they are the only windows in