In the years after WW2, the French railways, SNCF, began an ambitious project to electrify their mainline services. This was all part of rebuilding the railways after the war and, also, of re-establishing France’s reputation as a technical power-house.
By the 1955, French passenger trains held the world speed records for railways at just above 300kph. The engine was a type CC7100, built by Alstom.
There’s an old black-and-white film of the 1955 record on YouTube.
The more recent TGV record stands at almost 60okph! Also, powered by Alstom. If you want to know how fast 600kph is at ground level, watch the film on YouTube.
Don’t forget that film will tend to slow things down!