On my first visit to the US in 1981, New York was a must. The Empire State Building was historic, a cliche, but the World Trade Centre's two towers were new, fresh and dominant. I liked their bi-polarity and placed on the southern shore of Manhattan they rivalled the Statue of Liberty as an icon. I stood on the observation deck mesmerised by the prospects. The admission ticket is small and flimsy and devoid of the clutter on modern ticketing. It lay around drawers and envelopes of random memorabilia for two decades. I visited New York again, with my son Sean, then 11, two weeks before 911. We stood on Liberty Island and I reflected on the towers and on my first visit. Did the people in there sense they worked in a fabulous, world famous location or did they see it as just an office? Two weeks later the towers were gone. After 911 the ticket developed a strange intensity for me. It is a capsule of innocence, exuberant technology and confidence in strong simple forms. It is a documentary fragment of a landmark where geo-politics and the built environment catastrophically coalesced. I cannot really describe the feeling: I have been there, when it was there, then. Now it is not.