One major misfortune was the decision, taken at an early stage, that Spain's railways should be built to an unusual broad track gauge of 1674 mm (roughly 5ft 6in, or six Castilian feet). The choice of gauge was influenced by Spain's hostility to neighbouring France during the 1850s: it was believed that making the Spanish railway network incompatible with that of France would hinder any French invasion. As a result, Portuguese railways were also built to a broad gauge. This unfortunate political decision came to be regretted by future generations, as it hindered international trade, and also made railway construction more expensive.