Mediaeval Bulgaria has left numerous monasteries and churches. Some of the most visited are: Rila Monastery, Bachkovo Monastery, Rozhen Monastery, Troyan Monastery, Zemen Monastery,  Preobrazhenski (Transfiguration) Monastery, and Aladja Monastery. Also arousing big interest are the hundreds of churches which have preserved unique samples of the Bulgarian iconography, wall painting, and woodcarving schools, old manuscripts, church plates and utensils. Bulgarian monasteries have served as spiritual treasuries through the centuries, preserving Bulgarian Literature and religion in the times of Ottoman domination.