How does Google know where I am?
This is not tower triangulation.Android searches for access points even when wifi is turned off. If anyone (with GPS enabled) uses that wifi with any google services the bssid will end up in their database. Also if the google car has been nearby it has recorded the presence of the wifi access point at that location [1].Before you freak out: Apple and Microsoft also use access point information for positioning, although not as successfully.[1] https://googleblog.blogspot.se/2010/05/wifi-data-collection-...