Trinity conjures the perfect architectural image of an Episcopal church: Gothic Revival style, diminutive scale and detail, and an interior with impressive woodwork, memorial plaques, and notable stained glass windows. The architect planned a stone building, but, after receiving initial cost estimates, the vestry opted for brick. Thanks to pledges from “friends from New York” and to Bishop Peterkin's recommendation of an architect, construction commenced in 1882. When the building was completed, small porches sheltered the entries, and a mansard roof covered what may have been intended as the base for a future tower at the corner of the nave and chancel. These disappeared as a result of later extensions.
The church was consecrated in 1903, and in 1907 a polygonal chancel was added from designs by Edwin N. Alger. In 1924 Alger's successor, William F. Diehl, designed the Tudor Revival parish house. Built to the rear, on the site of the former rectory, the parish house almost overwhelms the church, but is set back far enough to be relatively unobtrusive. In 1961–1963 the nave was extended 28.5 feet toward 5th Avenue. Albert F. Tucker, architect for this work, also designed an addition to the parish house.
Some of the finest stained glass windows in the state are among Trinity's treasures. Several are signed by Louis Comfort Tiffany, including one depicting the Good Shepherd, a favorite subject of the artist. Later medieval revival windows, including those in the cloister that connects the church and parish house, are by the Willet Studios.
Cassell (c. 1842–1916), a charter member of the Baltimore chapter of the American Institute of Architects, also designed the Davis Memorial Presbyterian Church in Elkins ( RN10; 1894) (see Randolph County). Earlier, he had designed several Episcopal churches in Baltimore, where Bishop Peterkin had served before coming to West Virginia. Several years after his Huntington commission, Cassell designed the University of Virginia Chapel in Charlottesville. Of stone, as Trinity was intended to be, with its original covered entry still in place and a completed tower at the southwest corner of nave and chancel, the chapel there provides a good indication of the architect's original intention here.