In the city of Czestochowa at the monastery of Jasna Gora is one of the most famous paintings, the "Black Madonna of Czestochowa." First and foremost, this will be at least a half-day tour, not a quick in and out. It doesn't matter what religion you are, this must be seen. There is so much to see—a museum, a basilica, a chapel, alters—it's overwhelming.
There are stations of the cross standing on artificial rocks, and there are paintings of the station of the cross by Jerzy Duda Gracz, the most magnificent paintings you will ever see. Getting to see the painting of the Black Madonna is not easy; if you are not in the chapel itself, you are allowed to walk along the side, a quick walk along the side, definitely not enough time to do it justice. But a stop here is definitely on the must-see list.