Stained glass behind the altar

The central panel represents the Holy Trinity, surrounded by suns, stars and angels, and topped by the crown of thorns with three nails.

The panel to the right shows St. Wenceslas (top—the hem of his cape shows his name in Czech, “Svatý Václav”), Holy Roman Emperor Charles IV (holding a model cathedral—though he would only become emperor a couple years after St. Vitus was begun, he was already King of Bohemia and one of the cathedral’s major sponsors) and St. Vitus kneeling.

The left panel (currently being worked on, boooo) shows The Virgin Mary in royal purple surrounded by various Bohemian saints and kings. I’m pretty sure I recognise St. Ludmilla, with her white scarf.