Itaipu(biggest dam in the world) got me pretty impressed.
Some wiki-facts:
The amount of concrete used to build the Itaipu Power Plant would be enough to build 210 football stadiums the size of Maracanã. During its construction, the fabrication of concrete would have been enough to build, each hour, a 25 storey building.
The iron and steel used would allow for the construction of 380 Eiffel Towers.
The maximum flow of the Itaipu's spillway is 62,2 thousand cubic metres per second, it is equivalent to 40 times the average flow of the Iguassu Falls.
If Brazil were to use Thermal Power Generation to produce the electric power of Itaipu, 434 thousand barrels of petroleum would have to be burned every day
The volume of excavation of earth and rock in Itaipu is 8.5 times greater than that of the Euro Tunnel and the volume of concrete is 15 times greater. Over 50 million tonnes of earth and stones were removed.
The dam is 196 metres high, that is equivalent to a 65 storey building.
Around 40 thousand people worked in the construction.
That's pretty pharaonic. The military government loved pharaonic stuff.