I am trying to identify the buildings in this picture.
The one on the top left is in Vatican City, and the rest are also Catholic related but I'm not sure where they are.
All the pictures are from a postcard.
They are the Four Papal Basilicas in Rome:
Top-left: St Peter's Basilica:
Top-right: Basilica of Saint Paul Outside the Walls - most photos - eg. the one on Wikipedia - show the more detailed Western face, but the drawing above depicts the Northern face:
Bottom-left: Archbasilica of St. John Lateran:
Bottom-right: Basilica of Saint Mary Major: