Not all photos have location embedded on them, but many of them do. This is a tool that you can use online that scans the meta-data of a photo and shows you where it was taken.
You can also do this by hand on your computer or mobile device with a number of apps and tools available, but this is an online service that does all the exif data analysis for you.
Can't remember the location where you took that picture on your vacation? Upload your photo and find out where it was taken.