2.5 Euros - Henri I Vianden power station

The Henri-Orange pumped-storage hydroelectric facility on the Our River was completed in 1964, named after Henri I, Count of Vianden, a medieval lord whose castle still dominates the town above. Luxembourg's decision to invest in pumped-storage infrastructure reflected the duchy's strategic position in postwar European energy grids — the plant stores surplus electricity from the wider network by pumping water uphill, then releases it during peak demand. At full output it remains one of the largest such facilities in Western Europe.