So these traders began to take shortcuts cutting through houses and private courtyards to reach the opposite street.
Over time, these shortcuts began to develop into a well-known online grid of passageways called traboules.
The word comes from the Latintrans ambularewhich mean to cross.
Satellite image of Old Lyon.
Lyon has over five hundreds of these secret passageways.
Most traboules are on private property, and are hence closed to the public.
Others have been blocked off and are currently used as storage areas.
Only around forty or so traboules can be explored by tourists.
The city agreed to pay for maintenance, restoration, lightning and cleaning of the traboules.
In return the residents must keep the traboules open to the public from morning till evening.
The traboules were also used by the resistance fighting against occupying German forces during the Second World War.
The interior of a traboule in Lyon.
The building has an enormous six-floor stairway of facade.
Photo credit:philippe leroyer/Flickr
Many of the traboules are hidden behind doors such as these.
Some are marked, others are not.
