The Lusatian Neisse (Czech: Lužická Nisa; German: Lausitzer Neiße; Polish: Nysa Łużycka; Sorbian: Łužiska Nysa) is a 252 km (157 mi) long river in Central Europe. It has its source in the Jizera Mountains near Nová Ves nad Nisou, Czech Republic, reaching the tripoint with Poland and Germany at Zittau after 54 km (34 mi), and later forming the Polish-German border for a length of 198 km (123 mi). The Lusatian Neisse is a left-bank tributary of the Oder river, into which it flows between Neißemünde-Ratzdorf and Kosarzyn north of the towns of Guben and Gubin.
According to the 1945 Potsdam Agreement in the aftermath of World War II, the river became part of the Polish western border with Germany (the Oder-Neisse line). Being the longest and most notable of the three rivers named Neisse (Neiße) (German) or Nysa (Polish) (the two other rivers being Nysa Kłodzka (Glatzer Neisse) and Nysa Szalona (Wütende Neiße or Jauersche Neiße)), it is simply referred to as the Nysa or Neisse. An older Polish variant, no longer used, was Nissa.
The Muskau Park (German: Muskauer Park, officially: Fürst-Pückler-Park Bad Muskau, Polish: Park Mużakowski), is the largest and one of the most famous English gardens of Germany and Poland.
Situated in the historic Upper Lusatia region, it covers 3.5 square kilometers (1.4 sq mi) of land in Poland and 2.1 km2 (0.81 sq mi) in Germany. The park extends on both sides of the Lusatian Neisse river, which constitutes the border between the countries. The 17.9 km2 (6.9 sq mi) buffer zone around the park encompassed the German town Bad Muskau (Upper Sorbian: Mužakow) in the West and Polish Łęknica (Wjeska, former Lugknitz) in the East. While Muskau Castle is situated west of the river, the heart of the park are the partially wooded raised areas on the east bank called The Park on Terraces. In 2003 a pedestrian bridge spanning the Neisse was rebuilt to connect both parts.
On July 2, 2004, UNESCO added the park to its World Heritage List, as an exemplary example of cross-border cultural collaboration between Poland and Germany. It was added to the list on two criteria: for breaking new ground in terms of development towards the ideal man-made landscape, and for its influence on the development of landscape architecture as a discipline.