Old streets and architecture of Stockholm are amazing, just check it out!
Old Town of Stockholm is called Gamla Stan. This is literally translated as Old Town. Houses here are built in totally different époques, but most of them are dated 17-19 century.
German church (Tyska kyrkan) is built near the place were city gate was located, before it was moved for the last time. It was built and maintained by the German community, which was massive here and imported a lot of engineering to Sweden.
Big church (Stora kyrkan) was serving as the place for the prayers for the Swedish Royal family and everyone who lived in the Royal Palace, here in the Old Town.