To truly appreciate Belfast and its surroundings, 3 days is the recommended minimum. This timeframe allows you to dedicate Day 1 to the city's rich history, including the Titanic Belfast museum and a "Black Taxi" tour of the political murals. Day 2 is best spent on a day trip to the stunning Antrim Coast, where you can see the Giant's Causeway, the Carrick-a-Rede Rope Bridge, and Game of Thrones filming locations like the Dark Hedges. Day 3 can be used for the Cathedral Quarter’s vibrant food scene, the Ulster Museum, or a hike up Cave Hill for panoramic views of the city. If you are a fan of slow travel or want to explore more of Northern Ireland (like Derry or the Fermanagh Lakelands), extending your stay to 5 days would allow for a much more relaxed pace and a deeper dive into the local culture.