The Saints Boris and Gleb Cathedral is the main Orthodox church in Daugavpils
. It can hold 5,000 people, being the biggest Orthodox church in Latvia.
The cathedral is situated in Jaunbūve (Novoye Stroyenie) neighbourhood on the Church hill (Baznīckalns, Церковная горка), along with the Immaculate Conception Catholic Church, the Martin Luther Lutheran Cathedral and the House of Prayer of Daugavpils First Old Believers’ Community.
A previous church on the site was built in 1866 by the order of the Governor-General of the Northwestern Krai Konstantin von Kaufman for the needs of the local garrison and was consecrated in honour of the emperor Constantine I and his mother Helena. Usually referred to as the Iron church (Железная церковь, Dzelzs baznīca) because of its external cladding, it was dismantled and rebuilt at Tsargrad (now Jersika), where it still remains, following the decision to build a new garrison cathedral at the original site.