Tüyap Fuar ve Kongre Merkezi

It’s the biggest fair complex in Istanbul. Located a little bit away from the center in Beylikduzu neighborhood, it has around 16 pavillions and growing fast. There are several and important trade fairs all year around. There are many cafeterias and small restaurants during these fairs so you don’t starve or de-​caff :)
The best way to reach there is by Metrobus so you can avoid traffic jam. But usually these busses are very crowded. Otherwise you can get there by car or taxi but consider at least 1,5−2 hours in the traffic, one way!
There are several hotels nearby and next to the fair grounds so as a businessmen you may prefer to stay close to your trade fair, but meaning that you’ll be far from the city therefore you can’t make any visit to historical sights due to distances and traffic.