A penthouse with views stretching across the Bay Area is pushing for a new pinnacle in San Francisco real estate lavishness.

The two-level Four Seasons residence at the top of a new 45-story tower at 706 Mission is still under construction but is already listed for $49 million, the highest price ever asked for a condo in the city. The penthouse crowning 181 Fremont went on the market last month for $46 million.

The so-called "grand penthouse" will feature 10,000 square feet of living space — that's nearly the size of two basketball courts — and 4,000 square feet of outdoor terraces. In July 2020, the space will be available as a shell and the buyer will have the opportunity to customize the floor plan and finishes based on a number of options. (See some of those in the gallery above.)

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"We’ve been working with several interested buyers and one of the things we’re trying to do with each of them is understand how they like to live," said lead architect Glenn Rescalvo of Handel Architects. "We’ve already created several interior layouts, and we have plans for three bedrooms, four bedrooms and five bedrooms. We can move things around and engage a buyer to create a true residence that caters to their needs."

Rescalvo says a buyer can also customize the outdoor spaces with fire pits, a plunge pool, outdoor kitchen and Jacuzzi, among the choices.

The grand penthouse is part of a new Four Seasons Private Residences opening in the tower and the adjacent newly renovated historic Aronson Building in the heart of the city's Yerba Buena Arts District. The brand that's known for its hotels also operates 44 private luxury residences around the world. The new San Francisco location will offer 146 units total, with 11 penthouses, priced from $15 million to $25 million, and the grand penthouse among them.

While the penthouses are housed in skyscrapers, Rescalvo says the design is aimed at creating the feeling of living in a home.

"We wanted to create spaces that don’t feel apartment-like and that feel gracious and comfortable," said Rescalvo. "We wanted to create a space that has relationships with the outdoors and we have four distinct terraces across 4,000 square feet of outdoor space. This is what makes it feel more like a mansion and a home rather than a glorified apartment."

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The property will include personally customized service and access to experts such as a fitness guru, wine consultant and art curator. The buyer also has access to a club floor with indoor and outdoor gathering places, a fitness center, a lounge with a bar, private dining and a landscaped outdoor terrace with fire pits.

The penthouse is priced above many of the most expensive homes on the market in San Francisco right now. A massive mansion in a prestigious part of Pacific Heights known as the Gold Coast is selling for $39 million. A Russian Hill property spread across two lots with soaring bay views has been on the market for over a year and after a price cut this summer is going for $40.5 million.

"With this one you’re going in at $49 million and then you get to create your own space," said Rescalvo. "That elevates it to the next level. The outdoor space will take it to the next level, and the fact it has this homelike feeling will take it to the next level. And then you have the Four Seasons brand and the services."

Amy Graff is a digital editor for SFGATE. Email her at agraff@sfgate.com.