I should just preface this by letting you know that I have Irish and Polish heritage, so 1.) I am only going to talk about Catholic Churches, and 2.) I am probably going to talk about Chicago a lot. I will try to spare you from being oversaturated with Chicago content, but truly some of my favorite churches are in Downtown Chicago. I have had the pleasure of visiting many churches, ranging from your run-of-the-mill suburban parishes, to California missions, and even all the way to St. Peter's Basilica at the Vatican.
I have always loved this church for its pink marble (at least I think that is what it is). It is run by Franciscan Friars (Order Friars Minor), so you get to see friars in habits running the church during the day. I can't quite put into words how this place makes me feel, but it gives off this pleasantly eerie vibe. The shiny marble, the old hat clips on the back of the pews, the lack of windows due to being wedged in between two other buildings, it all just makes you feel like you're in a different era. I always stop here when I'm downtown with my mom, because she would stop in here during her lunch breaks (her office building was half a block away).
One of my favorite things about this parish is that it is (sort of) in our backyard. Bandera is a Polish settlement outside of San Antonio, so the town has a lot of Polish influence, and their Catholic Church is definitely not excluded from that. The combination of pinks and blues in this church is absolutely stunning, and I would absolutely recommend stopping here if you are ever in Bandera.