The cathedral was built in 1422 on the site of a wooden cathedral from 1412, dedicated to the Trinity, and is located above the grave of Sergius of Radonezh. In the 15th-16th centuries, heirs to the Moscow throne were baptized here and treaties were concluded, kissing the cross at Sergius's grave. Like the Assumption Cathedral in Zvenigorod, this is a four-pillar cross-domed church, standing on a basement and built of white stone. The building's decor became stricter: only a triple ribbon of carved ornamentation remains, encircling the walls, apse, and drum. The walls are divided by flat pilasters supporting the keel-shaped arches of the zakomaras. The forms of the church are simple and compact: the apses hardly protrude beyond the main cube, are raised to the same height, and the kokoshniks barely rise above the zakomaras of the facades. The smooth walls are inclined inward, corresponding to the narrowing of the dome's drum. The internal arrangement does not correspond to the facade divisions. The mausoleum-like church is spacious inside, with the pillars shifted to the east, and the altar area is small, which increases the church's capacity. This shifts the dome to the east, disrupting the centrality and balance: the western zakomaras are detached, and the portals are located closer to the apses. For symmetry, a three-part division of the facades with pilasters was preserved, which does not reflect the internal layout. The internal walls, devoid of decor, appear stricter than the facades. In the 16th century, a porch was added to the western facade, and in 1548, the Nikon Chapel was added to the southeast side. Between 1425 and 1427, the cathedral was painted by Andrei Rublev and Daniil Cherny. In 1635, the frescoes were replaced with new ones, preserving the old painting system. The wall paintings were repeatedly updated, and now the walls are adorned with frescoes from 1635, revealed during the restoration from 1949 to 1954. The original painting by Rublev has survived only on the slopes of the door in the deacon's room. In 1635, the Nikon Chapel was also painted, but the painting has only survived in the central zakomara above the apse and in the pilasters of the drum. The iconostasis was created by Rublev and Cherny around 1425-1427. Additionally, Rublev painted the icon "Trinity" for the cathedral, which was part of the local iconostasis. It also includes the icon "Sergius with Life" from the school of Dionysius. The cathedral houses a silver reliquary above the grave of Sergius of Radonezh, a specimen of Russian coinage. The silver canopy, a contribution from Empress Anna Ioannovna, was made in Moscow in the workshop of David Prikhva and installed in 1737.