Lavra, exterior of the Catholicon
The Catholicon (communal church) of the Lavra, with its large central dome, rising over a cross-shaped plan, stands in the midst of the monastic enclosure on the south slope of Mount Athos. Begun by Saint Athanasios in 963 with funding from Byzantine Emperor Nikephoros, this church provided a model for most subsequent Athonite monasteries. It is distinguished by its capacious western vestibule (the narthex or lite), designed to accommodate prayer and psalmody by monks during the offices, and processions on festal occasions, and by its domed side chapels. The apses or semidomes on either end of the transept (north-south cross-arm) accommodate twin choirs of monks and enhance the acoustics for the unaccompanied singing at the heart of the Orthodox liturgy.