The George R. Brown Convention Center is a massive building in downtown Houston that was built in 1987, and has since then seen numerous expansions and modifications to accodmate more conventions and exhibits. It hosts a great number of conventions that brings in people from around the world, for all fields, interests, and hobbies. You find events for whatever you are inclined to, from gun shows, to massive prayer services for any major religion under the sun.
Even though this venue is large, doesn't mean you are guarenteed to get in, so if you find yourself looking at a sold out event look up tickets at MyTicketIn.com!