St. Mary's Assumption is home to a shrine and museum for Blessed Francis Xavier Seelos, a German priest who came to the United States to minister to German-speaking immigrants.

Seelos died while serving as the pastor at St. Mary's Assumption: after visiting and caring for the victims of yellow fever, he succumbed to the disease himself in 1867.

It was declared a National Historic Landmark in 1974, significant as a rare and elaborate example German Baroque Revival architecture.

In 2005, Rice added text and pictures on her website that encouraged donations to St. Mary's Assumption to help repair the damage caused by Hurricane Katrina.

The choir organ was constructed by Pels & VanLeeuwen of Alkmaar, The Netherlands, in 1971 for the chapel of First Presbyterian Church of Royal Oak, Michigan, as that firm's Op.