 When the Portuguese colonised part of Goa in the sixteenth century, they based their operations in the central district of Tiswadi, notably in the international emporium 'City of Goa', now Old Goa.As threats to their maritime supremacy increased, they built forts on various hillocks, especially along the coast.In 1624, they began to build their fortified town on the headland overlooking Mormugao harbour.