Main altar and chancel of St. John the Evangelist Cathedral in Cleveland, Ohio, in the United States.

The sanctuary, Terce Chapel, and Chapel of the Blessed Sacrament were all designed by Rambusch Decorating Company of New York City. The steps leading from the nave to the sanctuary are made of white true marble with gray veining. The sanctuary floor is a white true marble with gray veining, with inlays of Verde Antique marble.

The four pillars are Botticino marble, and resemble fasces (rolls of papyrus, bound together, representing the way laws in ancient Greece and Rome were written down). However, each roll is interlaced with the others, a highly unusual pattern. Beneath the altar top is a solid block of breccia, fronted with a bas-relief of a pelican and her chicks. The pelican was once believed to feed its young with its own blood, and represents the Eucharist. The altar top is also Botticino marble and weighs 1,400 pounds.

When the cathedral was built in 1848, the altar was in this location. It was moved backward in the 1946-1948 reconstruction and separated from the nave with an altar railing. The altar was moved back to its original position, the altar railing removed, and other changes made to the sanctuary in 1977 in accordance with Vatican II.

At the back of the chancel is the Bishop’s chair, or cathedra. The cathedra is made of Botticino marble and the wall and seating associated with it is of Loredo Chiaro marble -- a light-brown breccia with purplish, cream, and green mottling. Yan H. Rieger sculpted the bronze coat of arms on the chair.

The reredo at the back of the apse is made of hand-carved Appalachian oak. It is 20 feet wide and 27 feet high, and consists of 850 pieces. The top-central niche is occupied by a statue of St. John the Evangelist, flanked by Sts. Peter and Paul. In the rank below are statues of St. Matthew, St. Mark, and St. Luke. There are 32 smaller carvings of angels around the central figures.

The hanging lanterns were designed by Rambush Decorating Company of New York City during the 1946-1948 reconstruction.

To the left is Terce Chapel, named for the fixed time of prayer of the Divine Office. Visible is an icon of St. John the Evangelist, given to the cathedral by the Byzantine Catholic Diocese of Parma in honor of the 150th anniversary of the Catholic Diocese of Cleveland. The icon depicts the saint sheltering the cathedral in his arms.

To the right is the Chapel of the Blessed Sacrament. The Tabernacle in which the sacraments rest, reredos and accompanying sculptures, candlesticks, and prie-dieux were designed, sculpted, and manufactured by the Rambusch Decorating Company of New York City during the cathedral's renovation from 1946 to 1948. The base of the Altar of Reservation, on which the Tabernacle rests, was fashioned from the Cathedral’s original baptismal font. The lamp above the Altar of Reservation is a lamp which hung in the cathedral santuary prior to the 1948 reconstruction. It was re-hung in 2016.