Hungarian Prime Minister Viktor Orban and German Chancellor Angela Merkel are commemorating on Monday the 30th anniversary of the “Pan-European Picnic.” The event on the border of Austria and Hungary considered to have helped lead to the fall of the Berlin Wall.

Bilateral talks were scheduled after a religious ceremony in the Hungarian border town of Sopron.

The chancellor on Saturday thanked Hungary for “having contributed to making the miracle of German reunification possible” by briefly opening the Iron Curtain on August 19, 1989, allowing 700 refugees from Communist-ruled East Germany to cross the border into the West, AP said.

In recent years, relations between Berlin and Budapest have grown frostier amid Orban’s hard-line stance against refugees and German criticism of his policies at home.