Worth to know - Białowieża national park from Wikipedia:
Białowieża National Park (Polish: Białowieski Park Narodowy) is a National Park in Podlaskie Voivodeship, in Eastern Poland adjacent with the border with Belarus. The total area of the park is 152.2 square kilometres (58.8 sq mi). It is located 62 km (39 mi) southeast of Białystok (Poland). It is known for the protection of the best preserved part of the Białowieża Forest, Europe's last temperate primaeval forest fragment that once stretched across the European Plain. It is home to the world's largest population of European bison (Polish: żubr), the continent's heaviest land animals.2 The border between the two countries runs through the forest, the Belovezhskaya Pushcha National Park is adjacent on the Belarus side of the border. There is a border crossing for hikers and cyclists within the forest.
From Wikipedia - about Białowieża forest
Białowieża Forest (Belarusian: ??????????? ?????, Biełaviežskaja Pušča; Polish: Puszcza Białowieska Polish pronunciation: ?pu?t??a ?b?aw??v??ska ( listen); Russian: ??????????? ????, Belovezhskaya Pushcha) is one of the last and largest remaining parts of the immense primeval forest that once stretched across the European Plain. The forest is home to 800 European bison, Europe's heaviest land animal.2 UNESCO?s Man and the Biosphere Programme (MAB) designated the Polish Biosphere Reserve Białowieża in 19763 and the Belarusian Biosphere Reserve Belovezhskaya Puschcha in 1993.4 In 2015, the Belarusian Biosphere Reserve occupied the area of 216,200 ha (2,162 km2; 835 sq mi), subdivided into transition, buffer and core zones.5 The forest has been designated a UNESCO World Heritage Site6 and an EU Natura 2000 Special Area of Conservation. The World Heritage Committee by its decision of June 2014 approved the extension of the UNESCO World Heritage site ?Belovezhskaya Pushcha/Białowieża Forest, Belarus, Poland?, which became ?Białowieża Forest, Belarus, Poland?.7 It straddles the border between Poland (Podlaskie Voivodeship) and Belarus (Brest Voblast and Hrodna Voblast), and is 70 kilometres (43 miles) north of Brest, Belarus and 62 kilometres (39 miles) southeast of Białystok, Poland. The Białowieża Forest World Heritage site covers a total area of 141,885 ha (1,418.85 km2; 547.82 sq mi).8 Since the border between the two countries runs through the forest, there is a border crossing available for hikers and cyclists.
Land of primeval forest, wildlife and mix of cultures
Polish eastern borderlands are a very interesting area. This is the place where three cultures meets - Orthodox, Catholic and Muslim. Worth to know is a culture of Tatars minority - these lands were given to them by the Polish king as reward for bravery in the battle. Tatar culture is very interesting and exotic, you can taste special and very unique cuisine, see the historic wooden mosques and the old Muslim cemetery. Besides cultural values, this region is the largest natural wealth of Poland - the two largest national parks - Biebrzanski (which is best in spring) and Bialowieski - natural wealth both these places are stunning - the only one primeval forest in Europe and unique backwaters of the Biebrza River is something worth seeing .