Smaller churches often have several apses. The largest and most complicated central based church from the 9th century is the church of St. Donatus in Zadar. Around its circular centre – with dome above – is a nave in the shape of a ring with three apses directed to the east; that shape is followed on the second floor forming a gallery. For that period, with its size and beauty, St. Donatus is comparable only with the chapel of Charlemagne in Aachen.