A red-brick tower inside the Olsztyn Castle is seen in Olsztyn, Poland, May 26, 2026. The city is known for its lakes and natural scenery. (Photo by Aleksy Witwicki/Xinhua)

This photo shows a view along the Lyna River in Olsztyn, Poland, May 26, 2026. The city is known for its lakes and natural scenery. (Photo by Aleksy Witwicki/Xinhua)

Swans swim with their young in a lake in Olsztyn, Poland, May 26, 2026. The city is known for its lakes and natural scenery. (Photo by Aleksy Witwicki/Xinhua)

Buildings and restaurants along the Lyna River are seen in Olsztyn, Poland, May 26, 2026. The city is known for its lakes and natural scenery. (Photo by Aleksy Witwicki/Xinhua)

An open-air amphitheater is seen in Olsztyn, Poland, May 26, 2026. The city is known for its lakes and natural scenery. (Photo by Aleksy Witwicki/Xinhua)

Tourists visit a square in the Old Town of Olsztyn, Poland, May 26, 2026. The city is known for its lakes and natural scenery. (Photo by Aleksy Witwicki/Xinhua)

A street view is seen in Olsztyn, Poland, May 26, 2026. The city is known for its lakes and natural scenery. (Photo by Aleksy Witwicki/Xinhua)