Kiev: Saint-Sophia Cathedral and Related Monastic Buildings, Kiev-Pechersk Lavra

Designed to rival Hagia Sophia in Constantinople, Kiev's Saint-Sophia Cathedral symbolizes the 'new Constantinople', capital of the Christian principality of Kiev, which was created in the 11th century in a region evangelized after the baptism of St Vladimir in 988. The spiritual and intellectual influence of Kiev-Pechersk Lavra contributed to the spread of Orthodox thought and the Orthodox faith in the Russian world from the 17th to the 19th century. [source]

I haven’t been here (yet).