Originally, the sanctuary was designed with a simple arch and communion rail. The altar and tabernacle were made of marble. In the 1870s, side altars and the stations of the cross were added as well as a coal-burning stove described to be so large it nearly filled the space inside the chapel.
Artists painted murals on the interior walls and a depiction of the Coronation of Mary on the ceiling in the late 1800s, but over the years the murals were painted over or lost in renovations.
A $12 million, 14-month-long renovation of the historic chapel was completed in 2015.