Complex sentence: They roughly mark the halfway point on a possibly historical route between Suceava (Stephen's seat) and the Hotin Fortress (Khotyn, now Kamyanets-Podilsky, Ukraine), the strongest fort on the northern border of medieval Moldavia.
Split into simpler sentences: They roughly mark the halfway point on the route between Suceava (Stephen's seat) and the Hotin Fortress (Khotyn, now Kamyanets-Podilsky, Ukraine). Hotin was the strongest fort on the northern border of medieval Moldavia.