In the cityscape of modern-day Heerlen, there are very few reminders of the once omni-present mining industry. Most of the typical mounts of mining debris that surrounded the coal mines have been removed or transformed into green hills during an operation called "van zwart naar groen" (from black to green). Even the tallest mine chimney of Europe, 'Lange Lies' (tall Liz) and her older brother 'Lange Jan' (tall John), once major landmarks, were demolished. One of the few remaining mining buildings (shaft 2 of the Oranje Nassau I) now houses the Dutch Mine Museum.