BERLIN — The night the Berlin Wall fell, 30 years ago this month, Waltraud Ziervogel’s husband, Kurt, came home with the news and urged his wife to join him in the joyous celebrations and a stroll through West Berlin, suddenly accessible to them for the first time in nearly three decades.

“I said, ‘Are you crazy?’ and I went to bed because I had the early shift,” said Ms. Ziervogel.

It may have been lost on her just then, but the world changed that night. When she pulled up the metal blinds of her sausage snack business at 4:30 a.m., the usually busy corner — just 400 yards from the wall — was even busier.

“It was like a big party. Everyone was up and happy and partying, and many wanted to buy a sausage — but I wasn’t allowed to take West money,” she said.

Three decades, tens of thousands of pork sausages and boatloads of curry-flavored ketchup later, Konnopke’s, the sausage stand under a subway overpass in the heart of Prenzlauer Berg that started its life in 1930 is still there, a monument to a working-class Berlin that has been all but priced out of existence — the all-night bars replaced by banks, upscale kitchen stores and vegan restaurants.