<P> New industries such as information technology, education, financial services and the arts have risen . Sydney's iconic Opera House was opened in 1973 by Her Majesty . A new skyline of concrete and steel skyscrapers swept away much of the old lowrise and often sandstone skyline of the city in the 1960s and 1970s, with Australia Square being the tallest building in Sydney from its completion in 1967 until 1976 and is also notable for being the first skyscraper in Australia . Since the 1970s Sydney has undergone a rapid economic and social transformation . As a result, the city has become a cosmopolitan melting pot . </P> <P> To relieve congestion on the Sydney Harbour Bridge, the Sydney Harbour Tunnel opened in August 1992 . The 2000 Summer Olympics were held in Sydney and became known as the "best Olympic Games ever" by the President of the International Olympic Committee . Sydney has maintained extensive political, economic and cultural influence over Australia as well as international renown in recent decades . Following the Olympics, the city hosted the 2003 Rugby World Cup, the APEC Australia 2007 and Catholic World Youth Day 2008, led by Pope Benedict XVI . </P> <P> Sydney is a coastal basin with the Tasman Sea to the east, the Blue Mountains to the west, the Hawkesbury River to the north, and the Woronora Plateau to the south . The inner city measures 25 square kilometres (10 square miles), the Greater Sydney region covers 12,367 square kilometres (4,775 square miles), and the city's urban area is 1,687 square kilometres (651 square miles) in size . </P> <P> Sydney spans two geographic regions . The Cumberland Plain lies to the south and west of the Harbour and is relatively flat . The Hornsby Plateau is located to the north and is dissected by steep valleys . The flat areas of the south were the first to be developed as the city grew . It was not until the construction of the Sydney Harbour Bridge that the northern reaches of the coast became more heavily populated . Seventy beaches can be found along its coastline with Bondi Beach being one of the most famous . </P>

Sydney is on the bank of which river