If anyone reading this will be in Stockholm and is interested in history I recommend attending "Riddarholmsdagen" Saturday 12 May. Most of the buildings on Riddarholmen are government buildings and are only open to the public on this day.
Like Gamla Riksarkivet (the old national archive building) which has a really cool iron slide from the time of the second world war that was built so that books and documents could be evacuated quickly if necessary.
More information about Riddarholmsdagen:
http://www.sfv.se/cms/aktuellt/riddarholmsdagen_2007.htmlhttp://www.royalcourt.se/dekungligaslotten/riddarholmskyrkan/aktuelltriddarholmskyrkan/5.124d504108b48b219780003537.html