One of the most conspicuous buildings of the town is the Bratislava Castle situated on a plateau 82 m above the Danube. A castle has existed on the site since time immemorial. It has been the acropolis of a Celtic town. Another castle is Devín Castle (now in ruins) in the borough of Bratislava-Devín. It is situated on the top of a high rock at the point where the March (Morava) river, which forms the boundary between Austria and Slovakia, reaches the Danube. It is one of the most important Slovak archaeological sites and has been – thanks to its excellent location – a very important frontier castle of Great Moravia and the early Hungarian state. It was destroyed by Napoleonic troops and is an important symbol of Slovak and Slavic history. Yet another castle turned into an English Gothic style castle in the late 19th century, is situated in the borough of Bratislava-Rusovce, otherwise known for ruins of Roman Gerulata settlements.