I saw this on CNN the other day...and I looked at it. It was pretty accurate on where I was... dates/times/address

1)unlock iphone
4)location services
5) system services
6) Frequent locations

look at your history.

To turn it off...Turn off Freq locations and clear history

if you turn it off, you wont be able to use your iphone as a reminder of time it takes to goto one location to another if you know how to do that. (siri tries to remember your routine) (15 mins from home to work....if I use the drop down menu)