The earliest surviving buildings to our times was the Trinity Cathedral. It was built after a vision of what happened at the successor of Sergius of Radonezh - abbot Nikon. In 1422 on the site of the wooden church of the same name by the Serbian monks, who sheltered the monastery after the Battle of Kosovo, began the construction of white stone temple. Construction lasted three years, and the next two years - his signature.

Now Holy Trinity Cathedral is a monument rannemoskovskogo architecture and the continuation of Vladimir-Suzdal architecture of XIV-XV centuries .  This modest little building, formed around him the whole ensemble of the Trinity-Sergius Lavra .  Chetverik temple like a cube with a slightly tilted inside the walls, thus creating a sense of perspective .  Outside the slope starts at the base, and inside - on the arches of portals, which improves visibility .  The plane of the facade is divided into three parts, ending keeled arches - zakomaras .  High light drum, located on the tetrahedral basis of Chetverikov, completed a glittering gilded helmet-shaped dome with a cross .  Gold is covered and tiered roof of the Cathedral .  Light drum is offset from the center of the apse, in order to visually balance the structure .  In addition, a large number of high window openings bathe the iconostasis .  Three of the apse of the Cathedral of equal height .  The central part of the altar stands a little stronger than the others . 

Later, in 1548, to the Trinity Cathedral on the south side of its Nikon built a church, as if recalling the abbot connection with his teacher. A year earlier, the abbot monk Nikon was canonized and placed over his coffin Temple. It is made in the style of Pskov, which has spread from Moscow architects of the XVI century. In 1559, with the same side of the house there is another outbuilding - a tent over the coffin of Bishop Serapion. Thanks to all the annexe Cathedral began to look multilevel.

The interior of the Holy Trinity Cathedral performed great Russian icon painter Andrei Rublev, a visiting Saint Nikon and Daniel Chorny. Unfortunately, the frescoes of that time have not survived. But iconostasis reached in its original form, with some modifications. Home church icon "The Holy Trinity" is now in the Tretyakov Gallery, and its copy of the iconostasis in the temple of the Holy Trinity-Sergius Lavra, together with other masterpieces of Russian painting of the letters of St. Andrei Rublev. The artist founded the monastery workshop painters, which learned a lesson many masters of Russian iconography.

Trinity Cathedral on a daily basis takes pilgrims and tourists from all over the world who come to venerate the holy relics of St. Sergius of Radonezh, resting here in a silver reliquary.

Trinity Cathedral, being the first stone church of the Trinity-Sergius Lavra, keeping its main shrine, became the central building of the entire monastery. There are two main roads converge Trinity-Sergius Lavra, in different directions and defining the layout. Outbuildings eventually surrounded the Trinity Cathedral, created a holistic architectural ensemble of the church, and the church, built on the territory of the monastery, complemented his picture. Restoring Laurus in 1938, architect I. Trofimov said that here observed proportion of so-called "golden section". It is observed in the height of buildings, and in the ratio of the volume. A removal of buildings from each other is determined by the height of the Holy Trinity Cathedral. For example, the Church of the Holy Spirit is at the distance of two heights of the temple, and the Cathedral of the Assumption - three.