The Troitse-Sergiev Lavra is a historic monastery located in Sergiev Posad, Russia. It's a significant religious and cultural landmark, known for its stunning architecture and rich history. The Troitse-Sergiev Lavra is one of the largest and most important monasteries in Russia. It's home to several churches, including the Trinity Cathedral, the Assumption Cathedral, and the Church of the Holy Spirit. The monastery also houses a museum, a library, and a theological academy.