I went to Kinderdijk (Child's Dyke), a world heritage site which is famous for its picturesque, quintessentially Dutch windmills. I reached there by first taking the metro to Zuidplein, and then transfer to bus 154 which took about 40 minutes to reach there.
When I returned to my hotel in the afternoon, the whole place was noisy with many people again. Many roads were cordoned off. Then I saw a procession of people wearing colourful costumes and trucks of people playing loud caribbean dance music. Oh, it's the Summer Carnival!
When I went to the Museum Boijmans Van Beuningen, the road outside the museum was part of the procession route. There were many people, and the gate of the museum seemed to be closed with a guard standing outside. I approached the guard and was allowed in after revealing my intention to visit the museum.
While inside the museum, I could still hear the loud drum music of the procession ouside.
The procession ended at around 5 pm, but the carnival carried on till late at night. Many people are crowding and dancing in the open space; while many others are drinking in the pubs and cafes. You really can feel the carnival spirit all over the place. Even the metro was packed with people (probably also partly because the tram lines had been suspended due to the cordoning of the roads.)