The World Trade Center was a complex of seven office buildings in the [?] district of [?]. The Twin Towers were [?] between 1966 and 1973. Both were 110 [?] tall, and respectively 417m and 415m high. They were then the world's tallest structures. 50,000 people used to [?] in the Towers, and about 200,000 [?] went up to the top [?]. There were 95 [?], and it took less than a minute to [?] the observation deck. In 1993, a truck filled with [?] detonated in the underground garage, killing 6 people and causing much damage. On [?] 11th, 2001, the Twin Towers [?] after being hit by two hijacked [?]. It took eight months to clear the debris and [?] became a place of pilgrimage.