"When you're in Street View mode in Google Maps, if a clock icon is displayed under the address at the top-left of the map then historical street view imagery is available there. Click down arrow under the clock to expand the dates when imagery is available. You can click the different dates on the timeline to preview the imagery.
Try visiting a location that is known to have historical street view imagery. For example, visit Google's home campus (1600 Amphitheatre Pkwy, Mountain View, CA 94043). Next open street view then you'll see the clock icon under the address showing dates for historical street view imagery."