The sprawling 1,000-acre campus, located along Saint Mary's Lake, was founded by Cardinal George Mundelein in 1921.
It is located about 40 miles north of Chicago.
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And the vast majority of priests currently at Chicago-area churches have studied there.
Father John Kartje, the rector at the seminary, joined ABC7 Chicago Wednesday to talk about the big week for the seminary.
"It's (the seminary's) really put its mark in the life and service of parishes in Chicago and throughout the nation," he said.
The seminary's campus is open to the public for daily tours.