Stockholm wonder: the Royal Swedish Ballet celebrates 225 years. (includes related article on the men of Swedish ballet)(Cover Story)

They call Stockholm the Venice of the North. Almost everywhere you walk--and what a city for strolling--you encounter water and bridges. And boats. Ferries, skiffs, fishing boats, pleasure yachts--you see them anchored along the elegant strandvagen or sailing past former royal hunting lodges to the Baltic Sea, yesterday's gateway to the fur, timber, and iron markets of a Northern Europe once ruled from Norway to Ukraine by conquering Swedes. I had imagined Stockholm to be a modern city, gleaming and clean. It is clean, and when it's sunny, the water looks like sky-blue glass. But…