The most significant architectural feature of Carlisle Cathedral is its East Window. The tracery of this window is in the most complex of English Gothic styles, Flowing Decorated Gothic. It is the largest and most complex such window in England, being 51 feet high and 26 feet wide. It has nine lights, and tracery, which, it has been calculated, was drafted from 263 points. The tracery of the window still contains much of its original medieval glass.