San Simeon, California CNN  — 

Perched atop a California hill more than a quarter mile above the Pacific Ocean, halfway between San Francisco and Los Angeles, Hearst Castle is a stunning tribute to the incredible wealth of one of the 20th century’s most important businessmen and his extravagant tastes.

Named after newspaper tycoon William Randolph Hearst, Hearst Castle is actually one mansion – Casa Grande – surrounded by three guesthouses, each larger than the average American home.

There’s also an outdoor swimming pool built into the hilltop that reopened in late August after a four-year, $5.4 million restoration project that, among other things, stopped a 5,000-gallon-per-day leak.

Neptune pool at Hearst Castle

The Neptune Pool is at the center of the Hearst Castle travel experience, so visitors from 2013 to present who were treated to a giant cavity in the ground filled with construction equipment may want to make another visit.

Hearst himself spent time at the castle throughout its nearly 30-year construction, from 1919 until 1947. He died in 1951.

It was first open to the public in 1958, and 700,000 people visit annually. It’s now owned and operated by the California State Park system.

Jim Allen, a former Hearst tour guide who’s worked at the castle for 30 years, took CNN Travel on a special tour of the property, sharing some secrets of the sprawling complex that a billionaire once called home. Allen now works as the property’s director of communications.

1. It was designed by a woman

William Randolph Hearst and Julia Morgan, the architect of Hearst Castle

Businessman and newspaper mogul William Randolph Hearst had previously hired the first female war correspondent and the first female editor of a Washington, DC newspaper. So it was no surprise that he turned to architect Julia Morgan when he wanted to build a quiet California escape.

Morgan was the first woman to get an engineering degree from a California state university. She also studied architecture at the renowned Ecole des Beaux-Arts in Paris, becoming the first woman to receive a certificate from the elite school in architecture.

She worked hand-in-hand with Hearst for more than two decades designing and building the estate.

2. The decorations came from amazing places

Roman columns dot the expansive courtyards surrounding Casa Grande and the guesthouses.

The courtyards are adorned with sculptures from Egypt. The pool is surrounded by Roman columns. The bedrooms have one-of-a-kind Art Deco ceilings from Spain.

And a lot it was bought at the firm now known as Sotheby’s. In the 1920s, the auction house was known as the American Art Association, and they sold expensive works of great historical value.

Jim Allen, our guide, declined to answer how much Hearst paid for the items, other than to say, “It’s shocking how relatively inexpensive it was.”

After World Wars I and II, many European countries were in dire economic straits and sold many of their national treasures. Today, many have laws in place to protect items they have left from leaving the country.

3. Hearst planted a small forest

Hearst Castle looms over the Pacific Ocean.

There is a reservoir a short distance from the hilltop and within view of the top floors of Casa Grande, but Hearst didn’t want castle views of a water basin.

So he had 7,000 Monterey pine trees planted on the hillside to block the view. A large number remain today.

4. Hearst had a bedroom in one of the guesthouses

Hearst used this bedroom in Casa del Mar while the main house was under construction.

Hearst’s first bedroom was a narrow room in Casa del Mar, named for its sweeping views of the Pacific Ocean below.

He slept here while Casa Grande was under construction, and he returned to the room in his later years when taking the stairs to his third-floor residence in the main house was too much.

5. Hearst owned land as far as the eye could see

Junipero Serra Peak, roughly 34 miles to the north of Casa Grande, was once Hearst's northern land border.

From a north-facing terrace, visitors can look out into the Santa Lucia Mountains, and if they squint they can see Junipero Serra Peak.

At one point, Hearst owned all of the land from the castle to the mountain. It’s 34 miles to the north of Hearst Castle. At his peak, Hearst owned more than 250,000 acres of land around the castle.

6. It’s not finished

An exterior wall of Casa Grande stands frozen in three stages of development.

As time went by and Hearst’s ambitions met the reality of his old age, construction slowed to a halt. The exterior of the castle is made from Utah limestone cut to look like a Spanish masonry building.

Underneath the limestone facade is steel reinforced concrete that’s earthquake resistant. One exterior wall in particular shows the construction frozen in three stages of development.

In addition to some exterior walls, there were also plans to build more rooms in the back of the main house and create a huge courtyard to look into from the higher floors.

7. There’s a room bigger than some houses

The assembly room in Casa Grande is bigger than the average American home.

The assembly room is where guests would chitchat while waiting for dinner to be served in the dining room next door. At 2,498 square feet, it was so big that there were phones placed at each end for guests to call across the room instead of walking across it.

8. The rare art is really rare

An original tapestry from the Deeds of Scipio Africanus series

Speaking of the assembly room, there are four original 16th-century tapestries from the Deeds of Scipio Africanus series hanging on the walls. Some of the same tapestries are in the Louvre in Paris – but theirs are copies.