If you take bulwark to mean fortification, support then antonyms would be weak point, weak link, weakness, defenseless or exposed.
The Bulwark was created in 1946.
A moat is a bulwark against intruders.
Bulwark is a noun when referred to a wall used as a fortification. It is a verb as in to defend or fortify as if with a bulwark
i need a bulwark in this unpleasent situation. =]
Bulwark Protective Apparel was created in 1990.
He regards the church as being the pillar and bulwark of the truth.
Their religious belief served as a bulwark against loss of hope.
There are many online places to find Bulwark clothing. Amazon, bulwark, workingperson, flameresistanceuniforms, and yahoo are just a few who carry this brand.
The English Channel has historically been a bulwark of England's defense.
A bulwark is a supporting structure, parapet, or the above-deck hull of a ship (mainly to reduce over-wash). Metaphorically, it is a defense; a support or protective barrier, as in "the price controls were a bulwark against rampant inflation."
Not sure about Bulwark Road, but there is an excellent website about the History of Helston on the link below.