Photo: Niels Elgaard Larsen - User: (WT-shared) Elgaard at wts wikivoyage, CC BY-SA 4.0 via Wikimedia Commons
Not big, but it does 24 hours a day in the summer.
© OpenStreetMap contributors
Svalbard Kirke
The world's northernmost church. Always open, and has coffee and cookies for the visitors. Also sells postcards, books, etc., – just leave the money in a bowl.
Spitsbergen Airship Museum
Displays materials and ephemera from the era of polar exploration using dirigibles and other aircraft, mainly by Norwegians, Italians and American explorers.
This museum features many displays about the human history of the archipelago, especially whaling and mining, as well as various exhibits about arctic flora and fauna.
Permanent exhibitions of Kåre Tveter, lithographies from the Recherche expeditions and a 'Svalbard collection' with maps, books and local currency. The adjoining café, shop and artists' workshops are free to visit.
The Russian settlement of Barentsburg is accessible from Longyearbyen by boat. Organised tours are available. Accommodation and meals can be found at the Hotel Barentsburg, for prices somewhat lower than you would find in Longyearbyen.
Across the Isfjorden (2-3 hours by boat). Scenic glacier across the bay, colored a striking blue. Drop a cube in your glass for an Arctic martini. Often combined with cruises to Barentsburg.