Source: WTL photograph© taken on site in Mérida.
Notes: With a telephoto lens we now see the slits above the decorative Roman urns and below the (non-) rose window. The slits in the wall were used as openings for sixteenth-century rifles to fire on attacking Mayans (and others, such as rebellious Spaniards or feared English and French pirates).
Humanities question: There are two kinds of fortresses implied herein; what are they?