The tripto catalogue lists 28 industrial heritage sites: collieries and ironworks, mines, bridges, tunnels and power stations. Almost all are family-friendly, and three are UNESCO World Heritage Sites.
Zollverein in Essen was once the world's highest-output coal mine; the site with its double-trestle headframe is free, while tours and the Ruhr Museum cost extra. The Völklingen Ironworks in Saarland is the only fully preserved ironworks from the industrial age, with blast furnaces and a viewing platform – under-18s and students go free. At the Rammelsberg Mine in Goslar, more than 1,000 years old, you ride a mine train underground. Hamburg's Old Elbe Tunnel from 1911 runs 24 metres below the Elbe through tiled tubes, free for pedestrians. The Gasometer Oberhausen hosts large exhibitions, and Dresden's Blue Wonder is a steel bridge over the Elbe from 1893, with two historic funiculars nearby.
Most sites in the catalogue are in North Rhine-Westphalia (8, mainly in the Ruhr), followed by Lower Saxony and Saxony.
In practice: allow two to three hours, and half a day for Zollverein or Völklingen. Tickets usually cost €10–17, with tours extra; at Rammelsberg there are combined tickets with up to three tours. It is cool underground, so bring a jacket. Many sites are open all year and work well in the rain.