In front of the castle stands the most known monument in Warsaw - the Sigismundus Column. It is a landmark for Warsaw and it’s a must to have a picture in front of it. It was built in 1643 by the king of Poland Vladislas IV in commemoration to his father Sigismundus III, who moved the capital from Krakow to Warsaw (he did a lot of other good things apart of that).
At the moment there is a book fair, and that’s the reason why there are so many tents around the column. The crowd on the contrary, is quite usual for this place, because this is the most common meeting spot in town.