The Westergasfabriek spent a century making the gas that lit Amsterdam's streets, then sat poisoned and empty, and now it's where the west of the city goes to spend an afternoon. Red-and-yellow brick halls in full neo-Renaissance dress, dropped into a long park — a gasworks turned living room.
Start at the Haarlemmerpoort, the 1840 city gate that marks the edge of the old centre, and walk into the Westerpark the slow way, along the water. The lawns hand you over to the brick: the Gashouder first, a 1902 gas-holder the size of a cathedral and just as empty inside, now a hall for club nights and fairs. Around it, Het Ketelhuis keeps three cinema screens in the old boiler house, and the Zuiveringshal — the gas-purifying hall, built with a ceiling meant to survive an explosion — holds galleries and a light show now.
Don't plan the middle; just wander the lanes between the halls. Then slip out the west end onto the Haarlemmervaart, the old canal to Haarlem, and follow its quiet green line to the tram on Van Hallstraat. The 5 takes you back in.
