The area prospered during the Viking Age, leaving a heritage of runestones, graves and monuments, while Lake Mälaren was part of the Baltic Sea. Sigtuna was founded just before AD 1000, as Christianity arrived, and Sweden was united as a single kingdom. With a royal mint and a bishop, Sigtuna was effectively the capital of Sweden until power shifted towards Stockholm and Uppsala in the 13th century. After three fires in the 17th century, Sigtuna was a ghost town for 250 years, revived in the 1910s as a nationalist project.
The Arlanda airport opened in 1960, and has expanded step by step. Märsta, at the railroad between Stockholm and Uppsala, grew side by side with the airport.
If you touch down at Arlanda, and you want a chronological approach to Sweden, you could rent a car at the airport, or take a local bus, and start exploring Sigtuna, going on to Uppsala or Stockholm.
Hiking, cycling and bathing during summer. Ice-skating and Nordic skiing during winter.
Christmas fairs in Sigtuna.
Vafflan's by the Sigtuna marina offers a selection of burgers (including vegan), quick eats, and drinks. The BBQ burger is particularly tasty. Sit by the dock and enjoy a lovely view over the water. Watch out for the birds, they are not shy about eating your food if you step away for even a few moments. The sparrows are particularly bold, and will hop onto your table waiting for a chance even as you eat.
Beware of pickpocketing at Arlanda Airport.