There was a time when I would have been paying closer attention to these things... but not only did I have more time, the world - my world - was a much smaller place.
In 1983 my parents took me to Chicago to an event, and I got to see the Sears Tower, since 1974 the tallest building in the world. It was incredible to see, to look down from the observation deck and see the ground some 1,450 feet away.
A couple of years later we visited New York, where we saw the World Trade Center - the twin towers were not so tall as the Sears Tower, but knowing now what would happen on 9/11 I am glad that I had that opportunity.
On my first trip to Asia I have had the opportunity to photograph some of the tallest buildings in the world again, none of which had even broken ground in 1985. I photographed:
#6 - Two International Finance Centre, Hong Kong (The IFC Building)
#8 - Shun Hing Square, Shenzhen, China
#10 - Central Plaza, Hong Kong
#11 - The Bank of China, Hong Kong
#15 - The Centre, Hong Kong
This evening I will kick that tally up to 7 of the 15 tallest buildings in the 
world, when I visit the Microsoft Offices in Tower 2 of the Petronas Towers... #2 and #3 on the list of the World's Tallest Buildings. I am excited about this, but disappointed that I will not be able to walk across the famous bridge that connects the towers; Noel tells me that it is only open during certain hours.
This will bring my personal tally to eleven... I will have seen eleven of the world's twenty tallest buildings (thirteen if you count the WTC), and ten of the top fifteen. Unfortunately in order to fill out the list I would have to visit Taiwan, Shanghai, Guangzhou, and Dubai.However for anyone who is interested, the buildings that I am missing are:
#1 - Taipei 101 (Taipei, Taiwan)
#5 - Jin Mao Building (Shanghai)
#7 - CITIC Plaza (Guangzhou, China)
#12 - Emirates Building (Dubai, UAE)
#13 - Tuntex Sky Tower (Kaohsiung, Taiwan)
...so I will continue to look up during my travels... and hopefully within the next couple of years I can knock that tally up to 14/15!