Riddarhuset was recommended by a Swedish friend. We made dinner plans as we arrived in Stockholm and asked the typical question 'where to visit' ? We enjoy touristy attractions and also the obscure and less obvious sights. Our friend mentioned a couple of interesting places, on that list was the House of Nobility. He told us to be mindful of the short window when scheduling a visit. In fact, the House of Nobility is only open between 11-12noon, something to keep in mind when planning a visit.
According to Wikipedia, the House of Nobility is a corporation and a building that maintains records and acts as an interest group on behalf of the Swedish nobility. Its main purpose is to maintain old traditions and culture.
We paid 6 euros per person to enter. In general, we found Stockholm fairly expensive, so 6 Euros was a steal. The building is beautiful, presenting a great history with finely decorated arts and interesting furniture. The paintings exudes a great history of 17th and 19th century of Swedish nobility. Sadly, we couldn't find our names on any of the crests.