Metro Line M4 (Budapest Metro) Metro Line M4 (Budapest Metro) Line 4 (officially: South Buda–Rákospalota (DBR) Line, Metro 4 or M4, and unofficially: Green Line), is the fourth line of the Budapest Metro. It opened on 28 March 2014. The first section, 7.4 km in length and consisting of ten stations, connects the southwestern Kelenföld vasútállomás located in Buda, and the eastern Keleti pályaudvar in Pest, under the River Danube. While three additional sections — one an eastern extension to Bosnyák tér, the second west to Virágpiac, and a third further east to Újpalota — have been planned, these remain unfunded by the Budapest city
Budapest Hungarians arrived in the territory in the late 9th century. The area was pillaged by the Mongols in 1241. Buda, the settlements on the west bank of the river, became one of the centres of Renaissance humanist culture by the 15th century. The Battle of Mohács in 1526 was followed by nearly 150 years of Ottoman rule. After the reconquest of Buda in 1686, the region entered a new age of prosperity. Pest-Buda became a global city with the unification of Buda, Óbuda, and Pest on November 17, 1873, with the name 'Budapest' given to the new capital. Budapest also