If you’ve got a few years of photos available on your iPhone, the new Memories feature in the iOS 10 Photos app can be a great way to go back and relive significant events from past years. Photos will go back and automatically scan through your photo collection for groupings of photos by people and places and put them in collections, and Apple has even put the intelligence in place to figure out holidays — based on your home country — and organize your Memories accordingly by paying closer attention to photos around those times of year, and putting appropriate titles on them.
If you’re not seeing holiday memories and you think you should, check the setting for Holiday Events under Photos & Camera in the iOS Settings app. Also be sure that your regional setting, found under Settings, General, Language & Region is set to the correct country — which holidays are selected are based on this setting.