At last they were in the Round Tower, and felt themselves slowly ascending. Up and up, and round and round and round on an inclined plane, they went--past curious niches in the wall, containing ancient monuments covered with Runic inscriptions; past a door leading to the university library, with its valuable collection of rare Icelandic manuscripts; slowly, on and on, until finally they reached the very top with its observatory, once the home of the great astronomer, Tycho Brahe. "Peter the Great once drove a coach and four to the top of this very same tower," volunteered Karl. "I've read all about that at school in Chicago. What a splendid view of the city we are having. It is all spires, and red roofs and gables built stairway fashion, isn't it?" "And how beautiful and sparkling the waters of the harbor look, all alive with ships, great and small," said Valdemar. "It certainly is a splendid seaport!" Far away, the Baltic, blue as the Bay of Naples, shimmered in the bright sunlight; and close at hand, at the various wharves, merchantmen, with valuable cargoes from far countries, were loading and unloading. It was a scene of busy life. The boys counted the flags of many different nations. No wonder the city had been named Merchant's Haven, or _Kjöbenhavn_. "What a good view of the coast of Sweden we get up here," said Valdemar. "And north of us lies Elsinore, the scene of Hamlet's tragedy. And, Karl, I'm sure that, on a clearer day, we could see Rugen, the German island, where, one day long ago, the Kaiser sat on the top of the cliff four hundred feet high, and watched the famous sea-fight between the Swedes and the Danes. But I don't like to talk about Germany. I'm glad that Aage is a soldier. Some day he will help us get Schleswig back again!" said patriotic little Valdemar. "And, only think, some of the geography books have even dared to call the North Sea the German Ocean! Kiel Harbor, now bristling with German war-ships, once belonged to Denmark, and so did the whole Baltic!" "Yes, and once the Danes were ruling half of England, Ireland, and Scotland, and they even gained a foothold in Normandy," said little Cousin Karl by way of consolation. "And the Germans once stood in terror of our great Vikings, who lorded it over the seas in every direction!" added Valdemar, with growing enthusiasm. "Their graves may be seen on both sides of the North Sea to-day. And wasn't it here, Uncle Thor, when an unusually severe winter had bridged the Baltic, that the Swedish king, Karl Gustav, led his army, horse, foot and guns, over the frozen seas where no one had dared to cross before, and finally took Copenhagen? But Denmark and Sweden are at peace now." "I'm glad that they are," replied Karl, "and that Norway and Denmark are, too, or we might not see King Haakon next Monday!"