The three Gas Holders, built in 1885, were central to Westergas' activities.The Municipality of Amsterdam took over the Wester and Oostergasfabriek on August 10, 1898. In the first years thereafter, production increased and major innovations and expansions occurred such as the construction of a 100,000m3 gas holder in 1903 at the Westergasfabriek. A watergas plant, later known as the Transformatorhuis, was also built here in 1904. The great advantage of a watergas plant is that it can produce quickly in a short span of time. Especially during sudden cold spells in Amsterdam, this was a very nice feature.

^{Haarlemmerweg 4 - 10, group of men in front of the completed 100,000 m3 gas holder of the Westergasfabriek, 30931 Collection Bureau Monumentenzorg: negative sheets}