Once Upon A Christmas 134 Main St, Port Jefferson, NY11777 Inside the Harbor Square Mall is a store where Christmas is celebrated 365 days a year. The ceiling is decorated with…More snowflakes, ornaments and stars. A giant reindeer greets customers and is often holding a sale sign and a large model train set runs along the back of the store. Unique merchandise of all kinds is loaded into this winter wonderland. The store also offers a wide variety of personalized items for non-Christmas occasions. On weekends during Christmas season, you can even find live reindeer doing in-store appearances before making their rounds with Santa.