The Polish town of Jaroslav (with the emphasis on the letter “o”) is located near the border of Ukraine. Few people know that it was named after the Rus prince Yaroslav Mudryi and from the 16th to 17th centuries belonged to the princes of Ostroh.

It passed to the princes of Ostroh as a result of a dynastic marriage between young Oleksandr Ostrozkyi and, already an orphan, Anna of the Kostka family. Anna's father Jan Kostka, the voivode of Sandomierz, had already died at that time, but the significance of the Kostka family, who were direct descendants of the first Polish Piast kings, was still well revered.

During those years, Mazovia and Warsaw were recently annexed to Poland (1526) ​​and the Mazovian nobility still had fond memories of their independence. Anna Koschanka's grandmother, who was also called Anna, was proclaimed Queen of Mazovia, but she never managed to maintain her independence. Therefore, it is not surprising that the choice of Prince Vasyl-Kostiantyn was made of the young orphan Anna. The royal ambitions of the Ostroh Prince could be clearly traced in this case as well.

Prince Oleksandr, who got married in 1592, made his main residence Yaroslav and built an attractive palace there. It is still located in the city center at Market Square. However, it is called “Orsetti family tenement house” today because of its later owner.

The life of the descendants of Oleksandr in Yaroslavl and nearby Lublin is shrouded in a mystical story. All the sons of Oleksandr died at a young age in Yaroslavl: Vasyl died in 1605, Kryshtof passed away in 1606, Oleksandr laid down his life in 1607, Adam-Kostiantyn died in Lublin in 1618, and Yanush-Pavlo gave his life in 1619. The deaths of Oleksandr’s last two sons were especially mysterious. The young princes Adam-Kostiantyn and Yanush-Pavlo were brought up of the Orthodox denomination under the guidance of Zyzanii Tustanovskyi. But after the death of their father, their mother Anna took care of their upbringing together with the Yaroslavl Jesuits. Pope Clement VIII personally took care that the princes became Catholics.

Studying at the Jesuit College of Yaroslav, the boys were not very keen on science. Actually, they were more interested in military affairs. Thus, when the Jesuit teacher said that philosophy was more important than the horse, Kostiantyn replied: “Dear Father, if there are a hundred thousand Tatars and a hundred thousand philosophers in front of them, obviously, the latter ones will not convince Tatars. They should be fought with”. Another case was told by Kaspar Nesetskyi. One of the sons, coming to the teacher, targeted the “Lives of the Saints” and pierced the book deeply with an arrow. The word that the arrow struck was “death”, which was a sign of imminent demise.

Returning home from the Warsaw Sejm on the 10th of April 1618, the young Kostiantyn Oleksandrovych, who had just turned 21, suddenly fell ill and died in Lublin. Exactly a year later, in 1619, the second son Yanush Oleksandrovych died and again in the very same Lublin.

The version that appeared almost immediately after the death of both princes, remains relevant. They both died in the house of the Lublin notorious nobleman Ludwig Poniatovski. Therefore, both princes could have died of poison or were killed in some other way. Both princes were buried in the church of the Yaroslavl Collegium of All Saints.

Prince Oleksandr was also buried in the Yaroslavl church. His daughter Anna-Aloiza transported his remains there from the Orthodox Epiphany Cathedral in Ostroh. She was buried in Yaroslavl as well. Then, the remains of her father and daughter were transported by the Jesuits from Yaroslavl to the Ostroh Jesuit Collegium, where they were destroyed by Russian soldiers in the first half of the 19th century.