You'll probably see St. Borys and Glib Cathedral across town before you actually find this important place of worship. Rest a while inside if the doors are open or just take in the facade from the street.
You'll find this principal church in Chernihiv. Once you've seen everything you want to at St. Borys and Glib Cathedral, consider visiting nearby Yurii Haharin Stadium, Chernihiv National University of Technology, and Alexander Pushkin Bust in Chernihiv.