The boundaries of what Torontonians consider downtown, where most of the city sights are located, are subject to debate, but everyone agrees on the southern cutoff—Lake Ontario and the Toronto Islands. The other coordinates of the rectangle that compose the city core are roughly High Park to the west, the DVP (Don Valley Parkway) to the east, and Eglinton Avenue to the north. A few sights beyond these borders make excellent half- or full-day excursions. An ideal way to get a sense of the city's layout is from one of the observation decks at the CN Tower on a clear day; the view is especially lovely at sunset.
Most city streets are organized on a grid system: with some exceptions, street numbers start at zero at the lake and increase as you go north. On the east–west axis, Yonge (pronounced "young") Street, Toronto's main north–south thoroughfare, is the dividing line: you can expect higher numbers the farther away you get from Yonge.