There is one point at which the glen
becomes extremely deep and narrow; the
sides descend to the depth of some
hundred feet, and are so steep as to be
nearly perpendicular. The wild trees
which have taken root in the crannies and
chasms of the rock have so intersected
and entangled, that one can with difficulty
catch a glimpse of the stream, which
wheels, flashes, and foams below, as if
exulting in the surrounding silence and
solitude.

This spot was not unwisely chosen, as a
point of no ordinary strength, for the
erection of a massive square tower or keep,
one side of which rises as if in continuation
of the precipitous cliff on which it is based.
Originally, the only mode of ingress was
by a narrow portal in the very wall which
overtopped the precipice, opening upon a
ledge of rock which afforded a precarious
pathway, cautiously intersected, however,
by a deep trench cut with great labour
in the living rock; so that, in its original
state, and before the introduction of
artillery into the art of war, this tower
might have been pronounced, and that not
presumptuously, almost impregnable.