Two of them are located near the entrance, the Giant Rose and Maman, the Gian spider, but if you go to the back of the tower, in the Sakurazaka Park, near the Roppongi Hills Residences towers, you can enjoy a sculpture of the South Korean artist Choi Jeong Hwa: Roboroborobo (roborobo-en) - that's my favorite.
The sculpture was made in 2003, it is 12 meters tall and represents a tower made from 44 cute, vivid colored little robots. The whole tower is made from plastic, one of the artist's favorite materials...
roboroborobo (roborobo-en), Roppongi Hills Mori Tower, Tokyo
EXIF info:
Fuji X100
Lens: Fujinon
Focal Length: 23mm
Aperture: F/5.6
Shutter Speed: 1/750s
ISO Sensitivity: ISO 320