Just a few short years ago, Lightspeed was a scrappy start-up with offices inside a Montreal townhouse. When it came time to look for bigger digs, the company enlisted Montreal-based architects ACDF* to help find a new location and transform it into the perfect space for the growing business. The founders of the point-of-sale and e-commerce software provider—whose employees tend to be on the younger side—had one requirement: the new offices needed to have a pool.

That proved almost impossible to pull off, but by the time the team came upon the abandoned Viger Train Station and Hotel by the old port of Montreal, an immense, turreted, château-style structure that had been abandoned for over a decade and recently slated for redevelopment, they happily settled on a “castle” in lieu of a pool.