Sigtuna was Sweden's first town, established by the Viking king Eric Segersäll in 980. It was soon minting Swedish coins and was a major centre of Christianity in the 11th and 12th centuries when it appears that there were close links with Russia. Runic stones and church ruins have been found from this period.
It can be approached from Stockholm by bus, and in the tourist season by boat, which would have a lot to recommend it. Alternatively, you could do a triangle; Stockholm, Uppsala, Sigtuna.
The place itself is small and picturesque; there is an arm of water with the main street parallel at one remove. The street itself is very attractive and has shops, mostly tourist-oriented and a bit on the expensive side. It boasts of being the oldest street in the country. Then there is the ruined castle and that is about it - beautiful but something of a tourist trap.
We went into a sort of courtyard cafe just off the main road which was very attractive looking and we enjoyed a cake there but did we pay for the privilege.
From journal Delightful Uppsala