Paola, a 'modern' urban area on the hill overlooking Grand Harbour, surprisingly shares a common past with Valletta. It too is a `new' town, designed by the Knights on a grid system like that of the capital city. The plan, devised by Grand Master de Paule, was for the town to serve as a summer resort taking advantage of the cooler breezes offered by its hilltop location. However, it did not succeed because the area lay near to what were then mosquito-ridden marshes near the harbour. It was not until the mid-to-late 19th century that Paola really grew. The town's population rose rapidly once the nearby dockyards expanded. Paola today has a landmark parish church. Built in the mid 20th century, the church is unusual for its unadorned and airy interior. Within Paola's tight grid of street, lies Malta's most precious prehistoric site: the Hypogeum underground burial chambers and temple, a UNESCO World Heritage Site.