Facade light: will the front be in the sun?
Short answer: Every facade faces one way, so it is only in direct sun for part of the day, and that part shifts with the seasons. St Peter's and the Quadriga are morning views; the Duomo in Milan, Notre-Dame and Petra's Monastery glow in the afternoon. Pick a landmark to see the hours for your date.
St Peter's Basilica
Today: Sun on the main facade 07:00–10:45, most frontal around 07:00; golden light 07:00–08:00.
Milan Cathedral (Duomo)
Today: Sun on the west front 13:25–17:05, most frontal around 17:00; golden light 16:00–17:05.
Florence Cathedral (Santa Maria del Fiore)
Today: Sun on the west front 13:20–17:00, most frontal around 16:55; golden light 15:55–17:00.
Notre-Dame de Paris
Today: Sun on the west front (towers) 15:35–17:20, most frontal around 17:15; golden light 16:10–17:20.
Sagrada Família
Today: Sun on the Nativity facade 07:40–08:00, most frontal around 07:40; golden light 07:40–08:00.
Cologne Cathedral
Today: Sun on the west front (towers) 13:20–16:55, most frontal around 16:50; golden light 15:40–16:55.
Brandenburg Gate
Today: Sun on the east side (Pariser Platz) 07:25–10:10, most frontal around 07:25; golden light 07:25–08:45.
Taj Mahal
Today: Sun on the main front (from the garden) 06:55–17:20, most frontal around 12:05; golden light 06:55–07:30 and 16:45–17:20.
Petra Treasury (Al-Khazneh)
Today: The Treasury facade gets no direct sun on this date above the cliffs in front of it; it stays in soft shade all day.
Petra Monastery (Ad-Deir)
Today: Sun on the Monastery facade 14:05–17:30, most frontal around 17:25; golden light 16:55–17:30.
Mount Rushmore
Today: Sun on the the four faces 06:45–12:55, most frontal around 08:15; golden light 06:45–07:50.
Neuschwanstein Castle (from Marienbrücke)
Today: Sun on the side seen from Marienbrücke 08:45–14:45, most frontal around 10:05.
How we calculate it
For every 5 minutes of the day we compute the sun's direction and height and compare it with the way the facade faces. Within 40° of straight on is full front light, 40° to 70° is side light that brings out the carving, and beyond that the facade is mostly in shade. Below 10° above the horizon the light is golden. Where cliffs or mountains stand in front of a facade, the sun also has to clear them.
Inside light (stained glass and the Pantheon beam) is on Light inside.