A former ad exec who sold his firm to Microsoft has spent the last 20 years restoring this mansion in Los Angeles — take a look inside

[Carmen Elsa Irarragorri Wyland]

When Leonard Fenton first bought his home — a 13,000-square-foot architectural masterpiece called "Artemesia" — he had no idea just how much work he would end up putting into it. He was in his 20s, and though he had previously restored homes while funding an earlier music career, he had never before worked on a project of this size.

Still, he knew a valuable opportunity when he saw it.

"I've always been an autodidact. I always jump into learning what I'm working on," Fenton told Business Insider.

At the time of the purchase, Fenton was heading up an advertising firm, Automotive Dealers' Marketing, that he would later sell to Microsoft.

He called up a few architects who specialized in preservation, consulted the National Trust's guidelines for historic properties, and got to work on the home, considered to be the largest ever built in the Craftsman style.

"The people and sources I consulted often didn't have the answer, but they taught me how to research and get the right answers," Fenton said. "I didn't just want a neoclassical house. I wanted a piece of art."

Nearly 25 years later — most of which he spent working on the home part-time, though he has been working on the restoration efforts full-time for the last six years — he plans to put the home back up for sale. It has been on and off the market for several years, but it's expected to be relisted for just under $10 million.

Leonard Fenton in his kitchen.

Let's take a look inside Artemesia.

The property spans nearly 2 acres atop the Hollywood Hills region of Los Angeles. Artemesia was originally built in 1913 for Frederick Engstrum, a construction magnate responsible for the Rosslyn Hotel downtown.

It's on a private road and is double-gated, which adds to its secluded feel.

As you approach, you get a sense of just how big the home is.

Fenton's goal was to preserve the original intent of the architect, Frank A. Brown.

But, he says,  some of the hardest restoration work happened on the parts of the house you don't see — the wiring and plumbing, for example. "This was a very big house on a significant piece of land, but it hadn't had real maintenance done since the '30s," he said. "We had to get all of the hard work done, then do the finishes."

The exposed wood beams are typical of the Craftsman style.

As is this porch, which has wide brick support columns.

Fenton says that now that he has finished work on Artemesia, he wants to expand to help other people restore their homes, and perhaps work on other, larger historic buildings.

"My approach is really different, and I think it has a place in the market," he said. "I want to get in the head of the architect and figure out what their original vision was, but also upgrade the amenities to make it a 21st-century luxury home."

Artemesia, for example, has a modern kitchen.

It has plenty of entertaining spaces, too, like this billiards room with its own fireplace.

This spacious ballroom would be the perfect setting for an upscale dinner party.

And each of the eight bedrooms has all of the modern comforts of home. Here's a look at the master bedroom.

The master suite has its own private sitting room.

But the other bedrooms aren't too shabby, either. This one's known as the "second master" and has a beautiful stone fireplace. Artemesia has six fireplaces.

More adventurous types could even sleep on the — rather large — porch if they wanted.

 The property's layout would definitely be appealing to those wanting to spend more time in the great outdoors.

There are all kinds of fountains, ponds, and waterfalls for the owners to enjoy.

Wide patios make the most of the house's hilltop perch.

There's also a carriage house with its own bedroom at the back of the property.

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There were a couple of rooms that had a bit to much white with in them.  But other than that this mansion is absolutely lovely!  I love the outside bedroom he created.  Would be a wonderful and tranquil place for meditation.

[Carmen Elsa Irarragorri Wyland]

Yes, it may be also a bit too much, but not for my taste. And yes, the kitchen is one that I do not care too much for, but the views must be fantastic, from everywhere!

Even approaching the place you begin to sense something beautiful.
I know the Hollywood Hills, since I had friends who lived in there, when I lived in so many different places in the Los Angeles area.