CEDAR RAPIDS — Firehouse Subs, a fast casual restaurant chain founded by former firefighting brothers Chris and Robin Sorensen, will open its first location in Cedar Rapids on Monday.The restaurant is located in Collins Crossing at 180 Collins Rd. NE, near Lindale Mall. Firehouse Subs is known for serving hot sandwiches on a toasted sub roll.John Chadima, owner of the new Firehouse Subs, said the restaurant’s firehouse décor is based on the founding family’s decades of fire and police service.