are of three stories. The lowest is square at the bottom
and octagonal above, the change being effected by a curved offset at two
corners, while at the third or western corner the curve has been cut
down so as to leave room for an eighteenth-century window, lighting the
small polygonal chapel inside, a chapel originally lit by two narrow
round-headed windows on the diagonal sides. In the second story there
are again windows on the same diagonal sides, but they have been built
up: while on the third or highest division--where the octagon is
complete on all sides--are four belfry windows. The whole is finished by
a crested parapet. The west front between these towers is very plain. At
the top a cresting, simpler than that elsewhere, below a round window
without tracery, lower still two picturesque square rococo windows, and
at the bottom a rather elaborate Manoelino doorway, built not many
years ago to replace one of the same date as the windows above.

Throughout the clerestory windows are not large. They are round-headed
of two lights, with simple tracery, and deep splays both inside and out.
The large transept windows with half octagonal heads under a large
trefoil were inserted about the beginning of the sixteenth century.

Inside the resemblance to Batalha is less noticeable. The ribs of the
chancel vault are well moulded, as are the arches of the lantern, but in
the nave, which cannot have been finished till the end of the fifteenth
century, the design is quite different. The piers are all a hollow
square set diagonally with a large round shaft at each corner. In the
aisle arches the hollows of the diagonal sides are carried round without
capitals, with which the round shafts alone are provided; while the
shaft in front runs up to a round Manoelino capital with octagonal
abacus from which springs the vaulting at a level higher than the sills
of the clerestory windows.[83] The most unusual part of the nave is the
vaulting of all three aisles, where all the ribs, diagonal as well as
transverse, are of exactly the same section and size as is the round
shaft from which they spring, even the wall rib being of the same shape
though a little smaller. At the crossing there are triple shafts on each
side, those of the nave being twisted, which is another Manoelino
feature. The nave then must be about a hundred years later than the
eastern parts of the church, where the capitals are rather long and are
carved with foliage an