Holy Trinity Cathedral, Russian Orthodox temple in Engels, Russia.

The Holy Trinity Cathedral is a temple with neoclassical design, distinguished by a large central dome and four smaller domes surrounding it. The interior is spaciously laid out and accommodates large numbers of visitors and worshippers.

The stone Holy Trinity Church was founded in 1816 in Pokrovskaya Sloboda and consecrated in May 1825 by Archimandrite Arseny of the Saratov Transfiguration Monastery. It was rebuilt in 1850 as a three-altar church with a bell tower and fence. In 1929 it was turned into a museum, the bell tower and domes were demolished in the 1930s, and the building later housed the city library. It became a cathedral in 2012.

The cathedral's name comes from its main altar, consecrated to the Life-Giving Trinity. The south side altar honours Saint Catherine, and a new iconostasis was installed there and consecrated on 7 December 1997; the Kazan side altar received its iconostasis during Holy Week 1998. The five-tiered central iconostasis was carved under Vladimir Shikhov from 1999.

Access to the cathedral is on foot, and visitors should dress respectfully and behave appropriately since it functions as an active place of worship. Visiting outside prayer times is best, as this allows more room and peace for exploring and observing the space.

The cathedral's bell ensemble includes a blagovest weighing over 5 tonnes, donated in 2019 by parishioner Oleg Ivanovich Zhukov; it is the largest bell in Saratov Oblast. An earlier bell of almost a tonne was brought from Voronezh in 2004. The first rector after the building's return, Archpriest Alexander Kerimov (died 2003), is buried in the churchyard.