Kutna Hora is incredible. There are 2 large gothic cathedrals there, 1 km from each other. The first one (next to the ossuary) has many martyrs skeletons clothed in gold and jewels, offered to the church by the Pope back in the 1500s (these are supposedly dead Romans from late Empire; their martyrdom is probably questionable).
The other cathedral has the most bizarre roof, one third roof, one third domes, one third bell tower, and a wonderful organ well worth the visit, and many beautiful frescoes depicting the work that made this place so rich : silver mining.
The first time I ever visited Prague we took an unplanned (no research) day trip to Kutna Hora just to see the bone church. The other cathedral down the street was amazing as well, but then to just be stumbling through the town and coming upon St. Barbara's Church was truly an experience. It got me hooked to continue travelling outside the US.
The other cathedral has the most bizarre roof, one third roof, one third domes, one third bell tower, and a wonderful organ well worth the visit, and many beautiful frescoes depicting the work that made this place so rich : silver mining.