Bridge is now. The line originally extended via Alfred St (now Alfred Street South), Junction St (now Pacific Highway), Blue St and Miller Sts to the engine house and depot in Ridge St. It used cable grip cars called "dummies" and un-powered trailer cars. A feature of these lines was the underground tram terminus at Wynyard railway station (the only one in Australia), and the tracks over the Sydney Harbour Bridge. Trams ran from Blue St, North Sydney over a now-demolished steel arch bridge over the Harbour Bridge Roadway, then over the eastern side of the harbour bridge (now road lanes), through a tram platform at Milsons Point railway station, before descending underground into platforms 1 and 2 of Wynyard station. Heritage listings North Sydney has a number of heritage-listed sites, including those listed on the New South Wales State Heritage Register: 36 Blue Street: Former North Sydney Technical High School (now Greenwood Hotel) 20 Edward Street: Graythwaite Falcon Street: North Sydney Sewer Vent 283a Miller Street: St Leonards Park 6 Napier Street: Don Bank 92-94 Pacific Highway: North Sydney Post Office 44 Union Street: Kailoa The following buildings are heritage-listed on other heritage registers: Chinese Christian Church, Alfred Street Christ Church, Walker and Lavender Streets Church of England Rectory, Lavender Street Houses: 11–37 Walker Street and 20–30 Walker Street Mercedes, 9 Walker Street St Francis Xavier's War Memorial Church, Mackenzie Street St Francis Xavier's Presbytery, Mackenzie Street St Francis Xavier's Church School Hall, Mackenzie Street St Peter's Presbyterian Church and Manse, Blues Point Road St Thomas's Church of England, West and Church Streets St Thomas's Kindergarten Hall, Church and McLaren Streets St Thomas's Church Rectory, McLaren Street Woodstock, Pacific Highway Commercial area The commercial district of North Sydney includes the second largest concentration of office buildings in New South Wales, with a large representation from the advertising and information technology industries. Advertising, marketing businesses and associated trades such as printing have traditionally dominated the business life of the area though these have been supplanted to a certain extent by information technology businesses. Corporations whose offices are in North Sydney include: Nine Entertainment Co, Cisco Systems, Vocus Communications, NBN Co, Novell, Sun Microsystems, AGL, Hyundai, AAMI, Sophos, Symantec, Nando's, Vodafone and NAB. Unlike other major suburban hubs within the Sydney metropolitan area, North Sydney has limited shopping facilities and almost no Sunday trading. There are four supermarkets (Aldi, IGA, Coles