Complex sentence: Sawi mosque is supposed to be one of the oldest mosques, which still exists though it has no roof now and most of its decorations have been damaged; glazed blue tiles were profusely used for ornamentation.
Split into simpler sentences: Sawi mosque is supposed to be one of the oldest mosques, which still exists though it has no roof now and most of its decorations have been damaged. Some portions of this mosque are still intact which indicate that glazed blue tiles were profusely used for ornamentation.