 Complete the following phrase:  The earliest evidence of human presence on the hill dates from the 2nd millennium BC. It was settled in the 4th century and a Byzantine city, tentatively identified with Zikideva, was constructed near the end of the 5th century, on the grounds of which the construction of the Bulgarian stronghold was begun in the 12th century. After the Vlach-Bulgarian Rebellion and the establishment of the Second Bulgarian Empire with its capital in Veliko Tarnovo, the fortress became the most important one in Bulgaria, often compared with Rome and Constantinople in magnificence. In 1393, the stronghold was 