In 1638, the construction of Santa Margherita fortifications began around Bormla but work stopped soon after due to a lack of funds, and they remained in an unfinished state.

[1] Construction of the Civita Cotonera and conversion of the earlier fortifications into the Santa Margherita castle, commenced in 1670 but following an outbreak of the plague, which only helped to put more pressure on the Order's already depleted funds, work was discontinued.

Contrary to Grandmaster Cotoner's plan for a castle at the centre of the new city, the Santa Margherita was continued as a line of fortifications.

As part of this project the British also built the Fort Verdala on the same site that Grandmaster Nicolas Cotoner had intended to build his castle.

The Cottonera Lines consist of the following bastions and curtain walls (going clockwise from Kalkara Creek to French Creek): Today, St. Laurence Demi-Bastion to Notre Dame Curtain fall within the limits of Birgu, while Notre Dame to St. Paul Bastions fall within the limits of Cospicua.