When you’re in the Street View interface, you will now see a small clock icon on the page. Once you click that, a preview image with a timeline underneath it will appear and allow you to see the older images.
It looks like Google’s Street View cars pass by most locations about twice per year. There is a bit of variation here, however, and some urban areas especially have more historical images available while some rural areas may have fewer. In many regions of the world, Google only started collecting this imagery in the last few years (it launched in the U.S. in 2007), so that may also limit the availability of historical images.
Google tells me this update is meant to be part of the company’s effort to “create a digital mirror and true record of the world.”
The update is going live globally today. For now, it will only be available in the desktop version of Google Maps and it is unclear if Google plans to bring this feature to other versions of Maps later.
Source: Tech Crunch