First constructed in 1914, the Kelenföld Erőmű (power plant) was, at the time, the largest electrical generation plant in the world, which at its peak supplied 4% of the power in Hungary and over 60% of Budapest. However, it will likely be best remembered by history as home to one of the best-preserved art-deco control rooms, designed by Kálmán Reichl and Virgil Borbíró.
This specific control room was built between 1925 and 1927 and was operational all the way until 2005 when it was decommissioned. The control room is currently protected by Hungarian law, ensuring it won't be torn down, although this protection is not the same as preservation and restoration.
Tours were conducted in the past, but unfortunately, the operator no longer seems to offer them. What a shame more people can't see this place; the photos don't really do the art-deco ceiling justice—it's more amazing in real life.
