Berlin U-Bahn U2

U2 also opened in 1902, on the same first stem line, and grew into an east-west trunk running from Pankow through Alexanderplatz, Potsdamer Platz, and Zoologischer Garten out to Ruhleben. It reached Ruhleben in 1929 and made its last extension, north to Pankow S-Bahn, in 2000.

The Wall split the line in 1961, and it ran for years as two stubs, one in the east and one in the west, with the central stretch past Potsdamer Platz closed. Reconstruction reconnected it in 1993 under the name U2. Most stations sit underground and are now step-free, but the elevator retrofit is not finished, so confirm access before you count on it.