On the worldwide technology trade show circuit, the largest of them all is the CeBIT show in Hannover, Germany, traditionally held in mid-March. I haven't attended for years, but I was at one time a regular, including the very last year (1985) of tech's inclusion as part of Hannover Fair, the world's largest industrial show. Yes, 20 years ago, you could see PCs and backhoes at the same show!
Since then CeBIT has prospered for the most part, and even now, with its IT-only focus, it's grown to an ungainly size and then started to suddenly shrink, which some would point to as the beginning of the end in the trade show lifecycle. (See my musings on Comdex, CES, etc, from last year in Obituary for the Trade Show?) Colleague Oliver Fritsch blogs about his views, from reading the local press in his native German about near-giveaway tickets and available hotel rooms in Hanover on the eve of the show, an all-time first.
My first visit, in the mid-80's, found me staying in Bremen, some 100 km away!