The first documentary references about Mezhyrich are found in the letter of 1396. Over time, it turned into one of the favourite residences of the princes of Ostroh, and was strengthened with earth defensive shafts with two entry gates Dubnivska and Zaslavlska. The ruins of the latter (Zaslavska gate ) have survived to this day.
In Mezhyrich there is Holy Trinity Monastery, which is the most prominent architectural monument not only among the monastic ensembles of Volyn, but also throughout Ukraine. The main and ancient building of the monastery is Holy Trinity Church, built by the princes Ostroh in the early XVI century. In 1606-1610, to the church were symmetrically attached the two two-story building of cells. The annex to Trinity Church buildings not only didn`t change, but, on the contrary, further underscored the importance of the temple that remained the tallest building. (Unfortunately, at the beginning of the 21st century, monks demolished the original bell tower and built a new higher, which began to dominate the temple). On the outer corners of both buildings are defensive towers.
The monastery contains miraculous icons of Virgin Hodegetria of the XVI century and St. Anthony of the XVIII century. One of the most revered miraculous in Ukraine is the icon of the of Virgin Hodegetria from the Mezhyrich Monastery. It was ordered by Prince Konstantin Ostrozky after a victory in the battle of Orsha. This image was very revered in the family of the Ostroh princes. Prince Yanush handed the icon of the Mother of God to the Mezhyrich Monastery in storage. In 1779, in a special honor and gratitude for miraculous deeds, the icon was decorated with a golden crown on the decree of the Roman Pope Benedict XIV. In 1866, the Russian Empress, the wife of Alexander the Third - Maria Feodorivna gave to icon a silver necklace decorated with six emeralds. Six more emeralds were embedded in the papal crown.