A 58-story luxury condo skyscraper in San Francisco is tilting and sinking - here's everything that's gone wrong in the last decade

The $350 million development was proposed in 2002, and construction began three years later.

The building's designer, Handel Architects, is responsible for the World Trade Center Memorial in Lower Manhattan.

At the time of its construction, the tower was the first skyscraper to be built in downtown San Francisco in two decades.

The tower opened to the public in April 2009.

At 58 stories high, the tower is the tallest residential building in San Francisco. Owners of the building's multimillion-dollar luxury condos enjoy panoramic views of the Bay Area and easy access to the city's downtown.

The high-rise is missing its 13th and 44th floors due to superstition among Chinese and American buyers.

In less than five weeks of sales, the tower sold $100 million worth of condos, with units ranging from $1.6 million to $10 million.

The tower's grand penthouse sold for $9.4 million in 2009.

In exchange for a hefty price tag, homeowners gained access to a 20,000-square-foot clubhouse, temperature-controlled wine locker, and concierge service, among other luxury amenities.

Since its opening, the tower has attracted celebrity tenants such as former 49ers quarterback Joe Montana, Giants outfielder Hunter Pence, and venture capitalist Tom Perkins.

All was well until 2010, when construction began on the Salesforce Transit Center (formerly the Transbay Transit Center) next door.

The agency responsible for the transit center, the Transbay Joint Powers Authority, hired a consulting firm to investigate how their excavation could impact the tower.

Their report found that the tower had sunk 10 inches into the ground — 4 inches more than the builders had predicted for the entire lifetime of the structure.

In 2014, a nine-month independent safety review determined that the sinking did not pose a safety risk.

More unsettling news came in 2015, when residents learned that the building had sunk 16 inches and tilted 2 inches to the northwest.

Tenants also complained of cracks in the walls of the parking garage and floors bubbling up from moisture.

The reports kicked off a feud between the tower's developer, Millennium Partners, and the Transbay Joint Powers Authority.

Millennium Partners claims the construction of the Salesforce Transit Center is responsible for the sinking.

In order to build the center, the Transbay Authority had to dig a massive hole in the shared land. Developers contend that construction workers pumped too much water out of the ground while the transit center was being built, causing the sand to compress and the tower to sink.

The Transbay Authority has cast blame in the opposite direction, arguing that the tower was built on an unstable foundation.

According to the agency, this caused the sinking long before the transit center moved in next door. The Transbay Authority also claims that the tower's concrete structure should have been anchored to bedrock to support its weight — a conclusion echoed by some homeowners.

In August 2016, residents filed a class-action lawsuit against Millennium Partners, claiming the developers were aware of the sinking as early as 2008.

Residents are seeking to recover the value of their condos, which have depreciated by an average of $320,000 per unit. Those attempting to sell have been forced to slash their listing prices or pull their units off the market.

In July 2017, the Millennium homeowners association told NBC Bay Area they were "stuck with nearly worthless condos."

Months later, the city attorney, Dennis Herrera, filed a similar suit.

"My office has a duty to protect all the taxpayers of San Francisco," Herrera said at a November 2016 press conference. "We are not going to sit by and allow a developer — or anyone else — to enrich themselves at the expense of others by hiding crucial information."

Hall of Famer Joe Montana also sued the developer, seeking a $2.7 million reimbursement for his condo and $1 million in "consequential damages."

Montana and his wife, Jennifer, received a reduced price on their apartment in exchange for promoting the building and allowing their names to be used in marketing material.

Their lawsuit names Millennial Partners, the Transbay Joint Powers Authority, and the San Francisco Department of Building Inspection.

In November 2016, the European Space Agency released satellite imagery that shows the tower sinking at a rate of two inches per year.

Their estimate is double what engineers originally predicted.

In July 2017, a report claimed once again that the building was safe, as residents complained of unexplained odors and openings in the walls.

The report, commissioned by the City of San Francisco, found that the sinking did not have "a significant effect on the building's safety" and did not compromise its ability to resist strong earthquakes.

While some homeowners were comforted by the report, others called it "superficial." The findings, which analyzed the building's current condition, were based on a previous report issued by the developer.

To stop the tilting, engineers proposed a $200 to $500 million renovation.

The fix would involve anchoring one side of the building to bedrock — which is more compact and tends to shake less than sand — and allowing the other side to continue sinking until it evened out.

The plan is one of many competing proposals to retrofit the skyscraper. One architectural design professor even suggested building a second structure next door whose counterweight could potentially stabilize the tower.

In September 2018, an apartment owner detected a large crack in his window on the high-rise's 36th floor.

That same day, residents reported hearing a series of creaking noises, followed by a loud pop. The discovery set off a month-long investigation, during which the city threatened to "yellow tag" the building, marking it as potentially hazardous to residents.

Around the same time, a drone inspecting the tower hit another building nearby, before crashing to the ground.

The investigation ultimately determined that the crack was caused by an "exterior impact" — not any sinking or tilting. But the engineering firm hired to inspect the window did not elaborate on what caused the collision.

That same month, the San Francisco Superior Court ruled that the Transbay Authority must pay a portion of Millennium Partners' legal bills.

A 2009 agreement stipulated that the Transbay Authority would protect the developer from "all claims, expenses, and liabilities" related to the shared land. According to the judge, this makes the authority responsible for two claims filed by the homeowners association, but not any claims related to Millennium Partners' possible attempt to defraud homeowners.

The San Francisco Chronicle now reports that taxpayers could be on the hook for up to $15.7 million in legal fees.

Most of the fees have been used to fend off claims by the developer and homeowners, including hiring witnesses and conducting scientific models, the Chronicle reported.

To date, nine lawsuits have been filed in relation to the tower's tilting and sinking.

Between 30 and 40 law firms are involved in the tower's legal disputes. The main case — which involves Millennium Partners, the Transbay Authority, the homeowners association, and individual tenants — awaits trial in June 2019.

Melia Robinson contributed reporting.