Just before Bratislava, the capital of Slovakia, the Danube forged a gap through the foothills of the Carpathian Mountain Range, known as the Porta Hungarica. After Bratislava the navigable Danube forms a reservoir leading to the enormous Dam and lock named after the nearby town of Gabcikovo. From here it forms the border between Slovakia and Hungary passing important towns such as Gyor and Komarno. At Esztergom the Danube becomes a Hungarian river and passes the ancient town of Visegrad. Here the river changes course by almost 90 degrees and forms the so-called Danube knee, flowing from north to south along the island of Szentendre past the town of Vac before it reaches Hungary’s magnificent capital city, known as the Queen of the Danube, Budapest.