Dmitri Donskoi replaced the oak walls with a strong citadel of white limestone in 1366–1368 on the basic foundations of the current walls; this fortification withstood a siege by Khan Tokhtamysh. Dmitri's son
Vasily I resumed construction of churches and cloisters in the Kremlin. The newly built Cathedral of the Annunciation was painted by Theophanes the Greek, Andrei Rublev, and Prokhor in 1406. The Chudov Monastery was founded by Dmitri's tutor, Metropolitan Alexis; while his widow, Eudoxia, established the Ascension Convent in 1397.
