Holidays is a neat mod that changes the appearance of cities and towns in Skyrim during the game's lore-based holidays.
When a holiday approaches, NPCs will start attending events for the upcoming holiday. You'll know when a holiday is approaching when a courier delivers a flyer or when you are able to view a monthly events letter at the bar located in each city tavern.
You'll notice festive lanterns, fireworks, and you'll even stumble upon some holiday discounts at various merchants.
You'll want to head into the game's various buildings (Inns, Temples, and Shops) to take part in the celebrations though some NPCs will celebrate outside.
This mod is Xbox One only at the moment.