The width of the bridge between parapets is 60 ft., except across the centre span, where it is 49 ft.
Some of these had been prepared with interior parapets and platforms of concrete for medium guns.
A grave defect in the design was that there was no covered communication between these casemates and the parapets.
In several cases there is a canal in the centre lined with stone, and protected by low parapets or banks, while almost every street and square is fringed with trees.
Most of the houses, and especially those of the planter aristocracy, are massively built of stone, with large grated windows, flat roofs with heavy parapets and inner courts.
