Was Gibraltar's land border fixed by treaty?

Was Gibraltar's normal land border fixed by treaty?

Only partly. The parties disputed the prescribed separation and treated the boundary more flexibly in practice than the formal measurements suggested.

The border was only loosely fixed by treaty. British and Spanish authorities debated how many local units of distance should separate their works, but neither side consistently treated the written limit as a rigid physical line. That ambiguity helps explain the fortification competition across the isthmus. A nominally neutral boundary could still become a militarized space shaped by construction, precedent, and practical occupation.