Germany and Poland staged festivities in twin towns on their shared border to mark the 20th anniversary of Poland's accession to the European Union.
German Foreign Minister Annalena Baerbock and Polish Foreign Minister Radosław Sikorski met in Frankfurt an der Oder and Słubice on Wednesday.
The two visited Słubice's Collegium Polonicum academic institution on the Polish side, then joined a festival and crossed the Oder Bridge to Frankfurt an der Oder in Germany.
Baerbock called May 1, 2004, an "incredible moment" for the continent.
On that day, the former Eastern Bloc states of Estonia, Latvia, Lithuania, Slovenia, Slovakia, the Czech Republic, Hungary and Poland, in addition to Malta and Cyprus, joined the EU, in what is described as the "big bang" enlargement.
"We as countries, as societies, as Europe found the strength to overcome the division of Europe and finally became a community of peace and freedom," Baerbock said.
"Today we experience how we are stronger as a common European Union of now 27," she continued, saying the unity went beyond the single market to encompass transport networks, joint law enforcement operations and cross-border relationships.
On the same day 20 years ago, then German foreign minister Joschka Fischer and his counterpart Wlodzimierz Cimoszewicz ushered in the new era of partnership on the Oder Bridge by shaking hands at midnight. The moment was welcomed by thousands of cheering people.
Poland and other former Soviet satellites are celebrating the anniversary of their EU accession against the backdrop of war, with Russia's full-scale invasion of Ukraine well into its third year.
The events also hold particularly significance for Berlin and Warsaw, as Germany's attack on Poland in September 1939 launched World War II.
