BERLIN (AP) — Germany is celebrating the 28th anniversary of the reunification of east and west, a process that Chancellor Angela Merkel says still isn't complete.

Germany was reunited on Oct. 3, 1990 following more than four decades of Cold War division, and less than a year after communist East Germany opened its heavily fortified border. While much progress has been made since, economic and other differences between east and west still persist.

The country's leaders are marking the anniversary in a ceremony Wednesday at Berlin's Staatsoper opera house.

Merkel, who grew up in East Germany, said: "28 years later, we know that what we call German unity is a process, a long road." She said it's important for Germans to "listen to each other."