Once a former leather factory, 1 Columbus Avenue, is one of those highly sought after loft conversion buildings with only 12 suites, each have their own distinct character and feel. 

The orginal building was built in 1902 and in 1997, Jackson Goad Architects renovated the building into what it is today. 

And while one could argue that any unit in this building is great, this penthouse unit is just a step above the rest. 

The main living area. 

"I've had so many clients over the years looking for authentic loft space, in smaller buildings. They are ultra challenging to find in my experience, and even more so when you want tremendous natural light as they are often divided up away from windows," explained realtor Paul Johnston. 

The large windows flood the home with natural light. 

But penthouse 401 has the unique benefit of oversized south-facing windows spanning 30 feet.

The unit has direct elevator access. 

And that, combined with 10-foot exposed wood ceilings, exposed brick, plus extensive and stylish renovations throughout, make it one of the most stunning hard lofts on the market today. 

The fireplace is especially cozy in the colder months. 

The main living space is airy and open concept with the dining room and kitchen. The living space also features a linear gas fireplace accented in hot rolled steel as well as an impressive 285-bottle wine cellar. 

The chef-worthy kitchen. 

The kitchen is a "home cook's dream," according to Johnston. It has a Wolf gas range, Sub-Zero fridge, a Miele dishwasher, a large eating counter and pantry space. 

The kitchen is directly across from the dining room making it perfect for entertaining. 

Plus the kitchen has a bank of east-facing windows, so you get glorious morning sunshine when you're making your coffee. 

The den space. 

This loft has two-bedrooms plus a den space that can be a flexible-use space, whether for a home office or a place to put your Peleton bike. 

The primary bedroom. 

Next to the den is the primary bedroom, which has a walk-in closet and a five-piece ensuite bathroom. 

The second bedroom. 

The second bedroom and the main bathroom are next to the foyer. 

The dining room. 

But the pièce de résistance is up the industrial staircase, opening up to a huge, private rooftop terrace with over 1,200-square-feet of additional outdoor space.

The private rooftop terrace.

The rooftop terrace boasts an outdoor kitchen that's perfect for summer BBQs, two firepits and a large pergola to provide some shade from the hot afternoon sun. 

Not to mention it has some nice views of the city over Roncesvalles. 

The outdoor kitchen on the rooftop terrace. 

"So not only is this space encircled by natural light, not only is it 2,000-square-feet inside, not only is it a penthouse, not only does it have direct elevator access, but it also has something so few heritage buildings offer - an enormous and private rooftop terrace," added Johnston.  

The primary ensuite bathroom with a large soaker tub. 

"If there's a 'boxes to be checked' when looking for a heritage loft, I think this hits every single one!"

The den leading into the primary bedroom. 

Penthouse 401 at 1 Columbus Ave. is currently listed for $3,745,000.