As a follow-up to Peter's story on the TD underground, we thought we'd let you know more about Toronto's PATH system. Here is what the Wikipedia says about PATH:

PATH is a 27-kilometre network of pedestrian tunnels beneath the office towers of downtown Toronto, Ontario, Canada. Unlike Montréal's Underground City or RÉSO, Toronto's system uses an integrated system of signs that makes navigation (somewhat) easier.

The PATH network's northerly point is the Toronto Coach Terminal at Dundas and Bay Streets, while its southerly point is the Metro Toronto Convention Centre's Convention South Building. Its main axes of walkways generally parallel Yonge Street and Bay Street.

The system began under city planner Matthew Lawson in the 1960s. Toronto's downtown sidewalks were overcrowded, and new office towers were removing the much-needed small businesses from the streets. Lawson thus convinced several important developers to construct underground malls pledging that they would eventually be linked. The designers of the Toronto-Dominion Centre, the first of Toronto's major urban developments in the 1960s, and completed in 1967, were the first to include underground shopping in their complex, with the possibility of future expansion built in. The city originally helped fund the construction, but with the election of a reform city council this ended. The reformers disliked the underground system despite their support for public transit, cycling, and especially walking as alternatives to the automobile. This opposition was based on the Jane Jacobs notion that an active street life was important to keeping cities and neighbourhoods vital and that therefore consumers should be encouraged to shop on street level stores rather than in malls (whether they be above ground or below). The system continued to grow, however, as developers bowed to their tenants' wishes and connected their buildings to the system. This also converted low-valued basements into some of the most valuable retail space in the country.