Ruin 11 is composed of a cluster of several small buildings, one of
which is situated on the north edge of the mesa somewhat east of Ruin
10 (pl. 25, _b_); another, called by Morley and Kidder Gibraltar
House, formerly of considerable size, was built on the sloping surface
of an angular bowlder (pl. 17, 21, _b_). Although many walls have
fallen, enough remains to render it a picturesque ruin, attractive to
the visitor and instructive to the archeologist, by whom it has been
classed as a tower. This building from the east appears to be a square
tower, but it is in reality composed of several rooms perched on an
inaccessible rock.