the top of El Caracol’s grand staircase is a tower, now rounded
by decay, but originally in the form of one smaller cylinder stacked
on a larger one. (Imagine a double-decker wedding cake.) To gain access
to the uppermost tower, you have to walk through a narrow winding
staircase. It is this staircase that earns the structure its name;
El Caracol means “snail.”
the half-ruined higher tower of El Caracol, three openings survive.
These three openings are small, narrow, and irregularly placed,
suggesting that they are actually viewing shafts. It turns out that
these windows do in fact align with important astronomical sightlines.
Looking through these windows a thousand years ago, observers could
have watched for Venus rising at its northern and southern extremes,
as well as the equinox sunset. The three window shafts that remain
in the upper tower of El Caracol seem to align with various celestial
events on the horizon.