“The rotunda is without question the single most inspiring space in the State House . . . Rotundas and domes are as traditional in capitol buildings as steeples are on churches, although this has not always been the case . . . Doane’s 1792 State House had a cupola but no dome, and it was not until Notman’s 1845 renovations/additions that the New Jersey State House had a rotunda . . . From surviving drawings of Notman’s rotunda, it was a very sophisticated work of architecture . . . The design of the present dome was changed even before construction began. The interior arrangement was subjected to further changes during construction and beyond . . . the rotunda had a chandelier, of which nothing is known except that it was removed and salvaged in 1905.” – Heritage Studies, Draft: The New Jersey State House at Trenton: An Historical and Architectural Investigation
“Probably the entire decorative scheme as it appears today is as originally designed with few alterations over the years. It is possible to examine in detail the rotunda and dome. The base and top marble members of the rotunda wainscot are dark cedar Tennessee. The trim around the panels are also Tennessee type marbles.
The twelve art-glass windows on the second and third floors of the rotunda, three on each side of the passageway, are opalescent ripple, a good quality glass (but not the cathedral or jewel) which were glazed in zinc, an old method of cementing that holds better than the lead used today. These windows, never repaired or cleaned, open at the bottom in two sections. They face east and west, the gold, green and antique purple of the stained glass capturing the morning and afternoon light adding to the architectural beauty of the rotunda. The middle west window contains the state seal framed in a half circle of laurel leaves with a fleur-de-lis border. The present design and colors, dictated by a 1928 law, were not used in this seal.
Post and McCord designed the rotunda balcony railing in 1888. As company spokesman, Mr. Post, said the fire breathing dragon supports and the eagle panels would ‘be very handsome.’ The architectural embellishments, symmetrical cornucopia rinceau, are made of cast iron with bronze plating. The eagle panels form the outside face of the balcony, the railing is made of three-inch-brass-pipe. Under the balconies, five inch ‘I’ beams decorated with metal rosettes are held in place by casted metal brackets in the form of dragons, that cantilever out to form supports.
At the interior lower section of the dome are eight green mural panels decorated with gold intertwining acanthus leaves and symbols. Two murals, repeated four times, show a caduceus, the wand of Mercury. Below the upturned wings are two heads of eagles set over the Latin inscription: Fiat Justitia Ruat Coelum (Justice is made [by man] (but) heaven rules). The other murals depict the symbol of Justice: two unsheathed swords crossed over a scale of justice.
The classical eccelectical elements of the rotunda and dome appear to meet at the third floor level when the first row of extant carved moldings, modillions, and rosettes take, just below the murals, the octagonal shape of the rotunda. The first row has three-quarter engaged pilaster arches on piers. The upper drum section has round arches with keystones and squared enlarged columns. On the next tier with alternating rectangular isinglass panels and fluted pilasters there is ornate cornices of dentils and modillions. The final tier has porthole windows with connecting moldings with a small molding similar to cyma reversa design.
The natural lighting, coming from the panels and porthole openings, contribute to the feeling of unlimited space, which may be the reason portraits have hung on the second and third floors of the rotunda since 1897.” – Zara Cohan, A Comprehensive History of the State House of New Jersey