Work has begun on a 20-year development project that will radically transform both Treasure Island and Yerba Buena Island into something virtually unrecognizable from what we know today. The plan, now two decades in the making, will come in at a rough cost of $6 billion, reports the Chronicle, and the San Francisco Business Times notes it will add around 8,000 new units in addition to developing large areas of park space.

The first phase of the project mostly involves demolishing older structures, in addition to some basic infrastructure work, and Curbed informs us that a slew of developers and financiers are champing at the bit to move things forward. Mayor Ed Lee is also excited about the the possibilities inherent in a massively underutilized piece of land.

The Treasure Island Development Authority says that, in addition to the 8,000 new units, this project will result in potentially up to 140,000 square feet of commercial and retail space, 100,000 square feet of office space, three hotels, and 300 acres of parks.

Around 25 percent of the housing will be affordable, notes the Chron, and the first phase of the project will include a hotel, a ferry terminal, and around 300 condos. As the population of the Bay Area continues to increase at a rapid clip, this huge project can't come soon enough.

As some of you may know, Treasure Island was built as the home of a world's fair, the 1939 Golden Gate International Exposition, and shortly thereafter it was leased by the US Navy and built up as a military base after the US entered World War II. Many of the original naval barracks, airplane hangars, and other buildings remain, and have been reused for various purposes in recent years.

Related: Amazing Trove Of Color Photos Show A Brand New Golden Gate Bridge & Scenes From The 1939 World's Fair