The Etymology of Bulwark
Bulwark and boulevard are the same word with very different fates. Both come from a Middle Dutch and Middle High German compound bolwerc, literally plank-work — a defensive wall built from heavy timbers and packed earth, a form of fortification well suited to the early gunpowder era when stone walls shattered under cannon fire. English borrowed it around 1418 as bulwark and used it for ramparts both literal and metaphorical (a bulwark of liberty, a bulwark against tyranny). French borrowed the same word as boulevart in the 14th century, also for a rampart. When European cities began demolishing their now-obsolete fortifications in the 17th and 18th centuries, the broad roads built atop the old rampart lines kept the name boulevard, which is how Paris ended up with the Boulevard Saint-Germain (literally, the Saint-Germain Rampart). One word, two opposite functions: defence in English, leisure in French.