The sculptured bronze door at the base of the monument, now kept locked, was originally open to visitors. Currently, the interior is open one day annually at Open House New York. The interior is entirely revetted with the same veined white marble used on the exterior. The interior is in two stages, with six niches in the lower stage, corresponding to the exterior basement, and an upper stage of tall Corinthian pilasters flanking plain panels; above is a ribbed interior dome with a central lantern. The mosaic on the floor is a star centered on a bronze relief medallion of the US arms, with crossed oak and laurel sprays.