Well morning brain asks you to consider Green Castle as The House of Windsor. Notice the green in their arms. Also, it's to the north of the other "castles" and North is the color green for the dark arts.
Finally, consider that Prince Philip went to hospital recently.
The first numbers - 578cDT324 - point to Australia on Google maps with a Duck duck go search. It has been removed by Google now from the search.
Map: https:// www.google.com/maps/dir/Current+Location /-37.47131,144.785156/@-37.474481,144.7915498,16z
Address: 345 Boggy Gate Rd, Clarkefield VIC 3430, Australia
That address doesn't link to much - but there is a charity of some sort once listed but now erased.
https:// en.wikipedia.org/wiki/ House_of_Windsor