The Ninjago Tower is a structure that appears to be something like the Town Hall of Ninjago City because the Mayor's office is there. This is Garmadon's target every time he attacks the city because as soon as he reaches the top, he will conquer Ninjago.
After Garmadon defeated Lloyd during his second attack on Ninjago, he used the Garma Mecha Man in order to climb the Tower. After he is victorious, he puts a flag and brings his volcano base on top of the Tower and throws a celebrating party.
NINJAGO Tower is the tallest building in NINJAGO City and, to Garmadon, a symbol of power. His dream is to conquer the city and transport his volcano lair to the top of this huge building, then have a big party. Of course, the hundreds of people who live and work in NINJAGO Tower might not be too happy about that, but that's the price they pay for having such a nice view of the city.
- According to a description on LEGO.com, Lloyd's apartment is located there, but in the movie it looks like it is located in a normal apartment building.
- According to LEGO.com descriptions, people live in multiple floors, though in the movie only office buildings can be seen.