One of the best things about the Viking River Cruises we've taken are the tours organized by Viking at the various stops. One of the best was of the National Village Museum in Bucharest, a huge park where the Romanians have gathered hundreds of buildings transplanted from various sites around the country. The buildings, ranging from homes, to churches, to rudimentary factories, make a fascinating introduction to the various styles and historical culture of Romania.
Unfortunately, we only had about an hour at the National Village Museum and so were barely able to get more than a rough introduction to the wealth of exhibits contained in over 270 transplanted buildings. I particularly wanted to spend more time with the large wooden machines which were driven by water power and used to dye cloth and make felt.
You can see more detail on the Wooden Churches of Maramures and the Fortified Churches of Transylvania by clicking on these links. Both of those collections of churches are UNESCO World Heritage sites in Romania.