Auckland Tower turned 20 yesterday.

Standing 328m tall, the Sky Tower is the tallest man-made structure in New Zealand and tallest free-standing structure in the Southern Hemisphere. When it was first opened it was among the top 10 tallest buildings in the world.

Since opening on August 3 1997, nearly 15 million guests have travelled through its upper levels to dine, take part in a SkyJump or SkyWalk or enjoy views of up to 82km in any direction.

The Sky Tower turned 20 yesterday and Kiwis can go up for free tomorrow.

SKyCity is also letting New Zealanders choose the colours that will light the top of the tower tomorrow, Friday and Saturday nights between 6pm-9pm.