At the beginning of the 20th century, impressive gas engines were constructed in Differdange to reuse blast furnace gas for energy generation. The most legendary among them was Gasmaschine Nr. 11, also known as the “Groussgasmaschinn”. Built in 1938 by Ehrhardt & Sehmer, this massive four-cylinder gas engine delivered over 11,000 horsepower and featured a flywheel with an eleven-meter diameter. The installation supplied both electricity and compressed air, serving as the beating heart of the steel plant until 1979. Today, the machine still stands in its original hall protected as a national monument and serving as a silent witness to industrial ingenuity.