The history of the city (founded in 1742) is closely connected with the history of the Troitse-Sergiev Monastery (The Trinity Monastery of St. Sergius), which was founded in the 14th century by St. Sergius Radonezhsky, one of the most revered saints of the Russian Orthodox Church. St.Sergius was one of the founders of broad monastic movement in Russia at the time of the Mongol yoke. He was the spiritual adviser of Prince Dmitry of Moscow who united the Russian forces to repel the Mongol punitive invasion in the great battle at Kulikovo field.

For many centuries the Sergius' monastery was Russia’s largest religious and cultural centre. The main shrine of the monastery is the Trinity Cathedral (1422), with the tomb of the saint himself. The Cathedral is also known for unique frescoes painted by the genius Russian icon painter Andrew Rublev and his teacher Daniil Cherny. The icon of Holy Trinity by Andrew Rublev, one of the most inspired masterpieces of the humankind, is kept now in the Tretyakov State Art Gallery in Moscow.

Nowadays the Trinity monastery is among the most important pilgrimage and educational centres of Russian Orthodox Church and one of the seats of the Russian Patriarch.