The latest warehouse going up in Katy will be the size of 12 football fields. The state-of-the-art building will span nearly 700,000 square feet and boast 36-foot ceilings. It will include a fast-response fire sprinkler system and LED lighting throughout. There will be enough parking for nearly 700 cars and more than 250 trailers. What this massive cavern lacks, however, is a tenant. But that hasn’t stopped developers from breaking ground on the largest spec industrial project in the Houston area. The project’s scope and speculative nature are signs of developers’ confidence in Houston as an emerging distribution center for brick-and-mortar and online retailers.