plans going back to Ancient Greece, including Italian Renaissance designs and the similar layouts of the American cities Philadelphia and Savannah–which, like Adelaide, follow the same layout of a central city square, four complementing city squares surrounding it and a parklands area that surrounds the city centre. The benefits of Light's design are numerous: Adelaide has had wide multi-lane roads from its beginning, an easily navigable cardinal direction grid layout and an expansive green ring around the city centre. There are two sets of ring roads in Adelaide that have resulted from the original design. The inner ring route (A21) borders the parklands, and the outer route (A3/A13/A16/A17) completely bypasses the inner city via (in clockwise order) Grand Junction Road, Hampstead Road, Ascot Avenue, Portrush Road, Cross Road and South Road. Suburban expansion has to some extent outgrown Light's original plan. Numerous former outlying villages and "country towns", as well as the satellite city of Elizabeth, have been enveloped by its suburban sprawl. Expanding developments in the Adelaide Hills region led to the construction of the South Eastern Freeway to cope with growth, which has subsequently led to new developments and further improvements to that transport corridor. Similarly, the booming development in Adelaide's South led to the construction of the Southern Expressway. New roads are not the only transport infrastructure developed to cope with the urban growth. The O-Bahn Busway is an example of a unique solution to Tea Tree Gully's transport woes in the 1980s. The development of the nearby suburb of Golden Grove in the late 1980s is an example of well-thought-out urban planning. In the 1960s, a Metropolitan Adelaide Transport Study Plan was proposed to cater for the future growth of the city. The plan involved the construction of freeways, expressways and the upgrade of certain aspects of the public transport system. The then premier Steele Hall approved many parts of the plan and the government went as far as purchasing land for the project. The later Labor government elected under Don Dunstan shelved the plan, but allowed the purchased land to remain vacant, should the future need for freeways arise. In 1980, the Liberal party won government and premier David Tonkin committed his government to selling off the land acquired for the MATS plan, ensuring that even when needs changed, the construction of most MATS-proposed freeways would be impractical. Some parts of this land have been