One of the most beautiful cathedrals I've ever stepped foot in, and I am a faithful patron of visiting cathedrals when I travel. On the "Buda" side of the river in Budapest, this cathedral sits atop a hill with a magnificent vista of the city beyond.
When I first walked in, I thought the church was tiled in mosaics. Instead, it is painted on every surface in Belle Epoque style images and geometric shapes. Apparently it was painted in the late 19th century and recently restored.
Not to be missed. Bring your binoculars. There is a lot to see. Be sure to go upstairs to the treasury for even more magnificent views, especially of the Art Nouveau angels.
In various places you will see the older medieval stone work with lions, saints and peasants. There is a black Madonna in a side sanctuary reserved for prayer and devotion.
Afterwards walk through the old city neighborhood down to the river. It was heavily destroyed in World War 2 but still has a magical feel of the peaceful old city of artists, musicians, and philosophers.