The first settlement to be called Zagreb developed on the east bank of the Medveščak stream (covered over in the 1880s and now Tkalčićeva street). The bishopric was founded here in 1094 and the first small church was built. The area was known as Bishop's Kaptol. When Mongol Tartars inavded in 1241, some of the Kaptol inhabitants decided to build a safer, tortified settlement on the higher hill across Medveščak stream. They named this new area Gradec and in 1242 the king, Bela, issued a 'Golden Bull' proclaiming in the Royal Free City of Zagreb.In the later half of the 13th century, work began on the church, wich was later to become Zagreb Cathedral. Remains of the fortifications built around Kaptol can still be seen today.