to the right of the south door (portada sur) which is topped by fine decorations, there is a 16th-century clock tower. the south façade was initially symmetrical with two defensive towers but the clock tower now looks less imposing. the east gable is flanked by the unfinished 16th-century tower of st martin and the 40-metre-tall bell tower which was repaired at the end of the 19th century as it had been damaged by the earthquake which hit lisbon in 1755. the 16th-century rose window can still be seen.