'Getting ready for this I wondered about a lot of things," Swift says in the trailer. 'I wondered what it would be like to perform for 70,000 people. I wondered what it would look like if they were all lit up and dancing around like no one was watching. I wondered what would happen if I invited the most amazing artists in the world to come out with me and perform on my stage, would they do it? This is the '1989 World Tour.'"