Troitse-Sergieva Lavra (Троице-Сергиева Лавра) is a famous Russian monastery and is the historical monumental symbol of Orthodoxy (at one period in time it was the center of the Russian Orthodox Church).

Troitse-Sergieva Lavra is located northeast from Moscow in the center of Sergiev Posad, which was known as "Zagorsk" (Загорск) from 1930–1991.

Initially it was monastery posad. It was founded in 1345 by venerable Sergii Radonezhski, who built a wood church in honor of the Holy Trinity in Makovets hill where the Lavra is located and he also built a small monastery.

First there was set up community statute in the North of Russia. Thanks to Sergii Radonezhski and his high level authority as confessor the monastery was economically strong by the end of the 14th century. There were developed bookish (ink-horn term), iconography and decorative métiers.

In 1540-1550 the small monastery turned into a powerful citadel that was rounded by high rock walls with towers and this allowed outlasting the Polish siege in 1608–1610. But in the 16th century very popular and honorable among the rest of monasteries in Moscow eparchy, the Posad got "lavra" status in 1744 (it was the second after Kievo-Pecherskaya Lavra).

By the middle of the 18th century it was the richest Russian monastery and since 1814 — the place of Religious Academy. By the beginning of the 20th century Lavra had a big collection of manuscripts and books, sacristy that was unique by its collections.

After the October Revolution in 1917 the Soviet Committee closed Lavra in 1920. Lavra’s buildings were given to different civic institutes and often these building were used as residences.

Thanks to saving some building as museums Florenski (Флоренский) and his followers could prevent them from stealing and selling sacristy collection but overall many valuables were lost or transferred to other collections. Returned to Russian Orthodox Church in 1945 Lavra renewed as the monastery and the center of Religion education, there were also a lot of government structures of the Moscow Patriarchy.

In 1960–1980 by conducting architect V.I. Baldin (В.И. Балдин) there were done some restoration works. However after 1983 the center of the Moscow Patriarchy moved to Danilov Monastery (Данилов Монастырь), the Lavra maintained its high level status as the most important center of religious education.

The monastery is renowned for its choirs.