Complex sentence: Unlike in most countries where the construction of railways was left to private enterprise, the French railway system was constructed almost entirely by the state, and private companies were invited to work the railways under lease (of up to 99 years).
Split into simpler sentences: Unlike in most countries where the construction of railways was left to private enterprise. The French railway system was constructed almost entirely by the state, and private companies were invited to work the railways under lease (of up to 99 years).