The Trinity Dome is known to be the biggest mosaic dome found within the U.S., which is located right above the primary center of worship. The Holy Trinity, which is known as the Father, Son, and Holy Spirit, is at its core, surrounded by angels and saints. This dome blends national identification with heavenly power, symbolizing God's presence over the church. With a thoughtful approach, it is placed above the area where worship is conducted, serving as a place for comfort and protection. The Basilica is a national spiritual gift, as seen by its size and artistry. The dome incorporates saints connected to the American Catholic image, symbolizing how Catholic values were strengthed into the US through shared communal devotion and cultural migration. "During his visit to the Basilica of the National Shrine of the Immaculate Conception on September 23, 2015, Pope Francis blessed the preliminary segment of mosaic created for the Trinity Dome containing the words of the beginning and end of the Nicene Creed: “I believe in one God.” “Amen" (Trinity Dome n.d.).

The chapel was provided by the Dominican Order, a group closely linked to encouraging Rosary devotion. Mary's maternal and intercessory function in Catholic theology is seen within the carved sculpture of Mary carrying the Child Jesus in the middle. The sculpture is surrounded by fifteen symbolic flames that stand for the traditional fifteen mysteries of the Rosary. In addition to visually directing visitors through the spiritual framework of the Rosary, the design promotes silent prayer and meditation and reflects the Dominican goal of teaching and devotion by using spiritual art and sculptures. Instead of just theology, this environment reflects how religious standards serve as cultural carriers, turning European religious traditions into an American national identity.

Thousands of believers gather together in the Upper Church Nave, a large central gathering place for Mass and national holidays. It is intended to highlight togetherness by bringing individuals from all ethnic and cultural backgrounds together in a common place of worship. Serving the region as a communal center, it is not only a place for worship, but also a safe space where individuals can convene in unity, finding both spiritual guidance and a sense of belonging. Rather than memorial worship, this area symbolizes living religion. At the national level, it represents the idea of communal religious engagement. The Nave turns into a convergence point where national, ethnic, and social differences slowly combine into a sole national religious body and identity.

Overlooking the North Apse is Christ in Majesty. This is known to be the largest mosaic of Jesus Christ in the world, where the distance between one wounded hand to the other measures 34 feet. The scale of the art represents Christ’s role as both protector and redeemer, overlooking people with His power and sacrifice at once. Displayed across the walls above the sanctuary, the mosaic serves to reinforce the belief that divine power overlooks all worship within the Basilica. The large scale of Christ sitting above worshippers reinforces not just divine authority, but the belief that various communities are intertwined under one religious ideal.