Shepherds of Christ Ministries spent $55,000 to have the protective glass installed this weekend.
Last year, a teen destroyed part of the image when he shot out 3 of the building's window panes. The group hopes this move will prevent any future vandalism.
"There's a lot of people in the world and everyone has a free will and people can choose to do things that are wrong," says John Weickert, Shepards of Christ.
Since the Virgin Mary image was damaged, Shepherds of Christ says the number of visitors to the site has dropped by almost 50%. The group says donations are also down.
The teen convicted of damaging the image was sentenced last year to 10 days in jail.