When the basement was finished but while the work on the upper church was going on, in 1899 Fr. Synnott decided to have a chapel finished off in the basement of the new church. When the structure was sufficiently advanced, Fr. Synnott’s efforts were centered on the completion of the chapel, and on Sunday, June 17 1900, the Sacred Heart Chapel was dedicated. This chapel was used for all liturgical functions until the completion of the upper church in 1907, at which time it continued to be used each Sunday for the children’s Mass at 8:00. The windows of the chapel were designed by James Dougherty of New York and symbolically depict different teachings of the church. They are about all that remain of the original chapel for in 1967, under the past- orate of Rev. Raymond Mulcahy, (Assumption’s seventh pastor) the chapel was dismantled and remodeled into the present Church Hall.
Visible in the exterior perspective of the church are repeated buttresses, a typical characteristic of Neo- or Victorian-Gothic architecture. The foundation of the church which is 183 feet long and 115 feet wide at the rear vestries is made of granite quarried in Ansonia, while the upper levels which are 88 feet in height are constructed in Monson granite. The foundation goes down to a great depth; the walls at the base being six feet thick.
Since the church is built on a hill that slopes 23 feet toward the rear of the edifice, the walls thus acquire a greater depth as one goes down toward the back of the church. The slope of the hill is so pronounced that whereas the church floor is only a few feet above the front walk, three floors range along the vestries at the rear. The slate used in the roofing is from Brownsville, Maine while the timber supporting the roof is southern yellow pine.
As one stands before the main entrance, the facade of the church stretches some 98 feet with the bell tower protruding 12 feet closer to the street on the north end. The original plans called for the tower to be crowned with a graceful spire, 195 feet high, surmounted by a cross. This tower was never completed and consequently the church has no bells. In 2017, a new electronic carillon was installed to play familiar hymns in addition to cathedral chimes.
There are two stained glass windows in the tower entrance: the one on the south side is a representation of St. Patrick and the one on the north side is that of St. Bridget.
Fr. O’Dwyer remained in Ansonia until January 1876 at which time he was succeeded by Rev. Hugh T, Brady, who was pastor until 1886. During his tenure, Fr. Brady enlarged the church building, but it still was too small for the Catholic population of Ansonia which had grown from 1,000 souls in 1870 to nearly 4,000 souls by 1890.
The first Church of the Assumption was a white frame building with a projecting vestibule and tower, which supported a spire. The interior was very modest, the ceiling being in blue half-gables. The altar was wooden, painted white and gold. A large rose window was at the rear. The first Church of the Assumption was used exclusively until 1900. At that time the sacred chapel of the present church went into use, and consequently the first church continued to be used only on Sundays at 8:00 a.m. for a children’s Mass.
On October 7, 1909, the Italian Catholics of Ansonia organized their own parish which was to be called Holy Rosary. Since the present Church of the Assumption was completed in 1907, from 1909 until August 16, 1955, Holy Rosary Parish used the first Church of the Assumption as its place of worship, although the 8:00 a.m. Mass each Sunday was reserved for parishioners of the Assumption Parish. In 1955, the church was sold to Holy Rosary. The Church was badly damaged in the August and October floods of 1955, but each time was restored. Finally, in 1967, the first Church of the Assumption was demolished after Holy Rosary Parish dedicated its new Church on May 28th.