根据短文理解，回答下列问题。

      You will find traffic noise disappearing as soon as you arrive in Venice(威尼斯). So as you walk down the narrow (狭窄的) streets, you only have to avoid crowds of people. About 19 million travelers visit Venice for the enjoyable environment, art and food each year.

        Seeing Venice on foot is the best. You can walk through the city in about an hour. Look around St. Mark's Basilica and the Doge's Palace. But you should know walking along the streets isn't as easy as travelling on the city's canals(运河). The canals are Venice's “Streets”. And you can enjoy the Grand Canal, the Rialto Bridge and many wooden buildings.

      Venice is fantastic. You shouldn't miss it in your life. No matter how long you're in Venice, it will leave a pleasant feeling on you.

下图是14世纪人们对于世界的认识，打破这一认识的历史活动是（    ）