That has the potential to become quite a large list, Solivagant!
North American additions that come quickly to mind are
Quebec City, with a parade ground in the Citadel,
Rideau Canal, with a parade ground at Fort Henry,
La Fortaleza, with parade grounds at its forts, and
Yellowstone, with a parade ground at Fort Yellowstone. Presumably the
San Antonio Missions could also be an addition; I haven't yet seen a reference to a parade ground at the Alamo, but with a military presence there for many years, the men would have had to muster somewhere.
This brings up another idea: could we add a connection for Changing of the Guards ceremonies? It looks like there may be several sites we can add
from this list.