The Pétrusse (Luxembourgish: Péitruss, German: Petruss) is a river flowing through Luxembourg, joining the Alzette at Luxembourg City. It flows through the town of Hollerich.

Luxembourg (Luxembourgish: Lëtzebuerg, French: Luxembourg, German: Luxemburg), also known as Luxembourg City (Luxembourgish: Stad Lëtzebuerg or d'Stad, French: Ville de Luxembourg, German: Stadt Luxemburg, Luxemburg-Stadt)[pron 2], is the capital city of the Grand Duchy of Luxembourg (also named "Luxembourg"), and the country's most populous commune. Standing at the confluence of the Alzette and Pétrusse rivers in southern Luxembourg, the city lies at the heart of Western Europe, situated 213 km (132 mi) by road from Brussels, 372 km (231 mi) from Paris, and 209 km (130 mi) from Cologne. The city contains Luxembourg Castle, established by the Franks in the Early Middle Ages, around which a settlement developed.

As of January 2018, Luxembourg City had a population of 116,323, which is more than three times the population of the country's second most populous commune (Esch-sur-Alzette).

In 2011, Luxembourg was ranked as having the second highest per capita GDP in the world at $80,119 (PPP), with the city having developed into a banking and administrative centre. In the 2011 Mercer worldwide survey of 221 cities, Luxembourg was placed first for personal safety while it was ranked 19th for quality of living.

Luxembourg is one of the de facto capitals of the European Union (alongside Brussels and Strasbourg), as it is the seat of several institutions, agencies and bodies of the European Union, including the European Court of Justice, the European Court of Auditors, the Secretariat of the European Parliament, the European Investment Bank, the European Investment Fund, and the European Stability Mechanism.

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