Despite its benign appearance today, Sydney Harbour once bristled with armaments. In the mid-19th century, faced with expansionist European powers hungry for new colonies, the authorities erected artillery positions on the headlands to guard harbor approaches. One of Sydney's newest open spaces, Headland Park, has opened on a former military base. A walking track winds past fortifications, tunnels, and heritage buildings, several of which are now used as cafés, including the Tea Room Gunners' Barracks. The Sydney Harbour Federation Trust runs guided tours of the park on the first Sunday of the month at 10:30 am.