Ninjago Tower

The Ninjago Tower is a structure that appears in The Lego Ninjago Movie. It appears to be something like the Town Hall of Ninjago City because the Mayor's office is there. Also according to Ninjago.com descriptions, Ninjagans live in multiple floors, however in the movie only office buildings can be seen. This is Garmadon's target every time he attacks the city because as soon as he reaches the top, he will conquer Ninjago.

The Lego Ninjago Movie
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.com Description
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.

Trivia

 * According to a description on Ninjago.com Lloyd's appartment is located there but in the movie it looks like it is located in a normal appartment building.