Interesting though, the record wasn't established at the time of inauguration, because the 15 meters diameter clock was installed 2 years later, in June 2002, when the NTT DoCoMo company (which is the number 1 mobile phone operator in Japan) celebrated its 10th anniversary. Then, the skyscraper surpassed the Palace of Culture and Science from Warsaw, becoming the tallest clock tower in the world.
Here it is, photographed on a beautiful winter night from my favorite viewpoint, the Shinjuku Southern Terrace.
EXIF info:
Nikon D90
Lens: VR 18-55mm F/3.5-5.6G
Focal Length: 18mm
Aperture: F/6.3
Shutter Speed: 6s
ISO Sensitivity: ISO 200