Sacred Heart follows a basilica plan with a corner tower. The foundation is composed of Anamosa Limestone and the walls of the structure are brick, clad in rock-faced Bedford stone quarried in Indiana. The nave is nine bays in length, and they are divided by buttresses. The first bay is the tower section. The other bays contain either a tracery or paired lancet window, which alternate down the nave. The church measures in length and its nave is wide. Across the back, where the sacristy and St. Margaret's chapel are located, it is wide. The roof rises above the ground and the spire on top of the tower is tall. When it was completed the cathedral was the tallest structure in the Quad Cities.