Oakland County has offered up four of its most well-known yet currently empty properties to help Detroit — and the region — land Amazon's second headquarters.

Sources confirmed Friday that the Pontiac Silverdome, Northland mall, the former Kmart headquarters and the Palace of Auburn Hills have been submitted for potential inclusion in Detroit's forthcoming proposal to host the e-commerce giant's newest headquarters campus, which would bring an estimated 50,000 new jobs and billions in new investment to the area.

Three of the four megastructures have been vacant for years and two of them are facing demolition in the coming weeks. The fourth building, The Palace of Auburn Hills, held its last public event last month after having lost the Pistons to Detroit's new Little Caesars Arena.

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All four properties span dozens of contiguous acres — a desired feature for Amazon —and three are next to freeways.

It was not immediately clear Friday whether and how the Oakland County properties would fit into Detroit's proposal for Amazon. Some of the sites may work as satellite campuses for Amazon, sources said.

Detroit's bid is being headed up by billionaire Dan Gilbert and could include the city of Windsor. A representative for Gilbert's real estate firm did not return a message seeking comment for this story.

Matt Gibb, Oakland County's deputy executive, told the Free Press on Friday that the county is glad to be part of a regional effort aimed at bringing Amazon here.

“Our role ... is to support what Mayor (Mike) Duggan is doing for the city of Detroit because of the importance to Detroit of that particular project," Gibb said Friday morning during an Oakland County economic development event. “We made the commitment that we would support the regional effort."

Crain's Detroit has reported that Oakland County Executive L. Brooks Patterson is among the 59 people from across southeast Michigan and Windsor on Detroit's Amazon bid committee.

Sources said Oakland County recently submitted the four regional landmarks to the Michigan Economic Development Corp., which is organizing Michigan's bids for the Amazon headquarters. Two additional Oakland County sites were also on the submission list: a southern portion of downtown Pontiac and the Haggerty Corridor in Novi.

Grand Rapids is expected to submit its own bid for Amazon by the Oct. 19 deadline.

The Oakland County sites include:

Northland mall: This 125-acre property in Southfield was home to the nation's first regional shopping mall. The mall opened in 1954, closed in spring 2015 and was later bought by the city of Southfield. Demolition of the mall complex could begin as early as the end of the month and last until next fall.

This 125-acre property in Southfield was home to the nation's first regional shopping mall. The mall opened in 1954, closed in spring 2015 and was later bought by the city of Southfield. Demolition of the mall complex could begin as early as the end of the month and last until next fall. Pontiac Silverdome: The now-abandoned stadium opened in 1975 and has been used only sporadically since 2002, when the NFL's Detroit Lions moved to Ford Field in Detroit. Its demolition could begin before year's end.

The now-abandoned stadium opened in 1975 and has been used only sporadically since 2002, when the NFL's Detroit Lions moved to Ford Field in Detroit. Its demolition could begin before year's end. Old Kmart headquarters: This architecturally distinct building is located at 100 W. Big Beaver Road in Troy. It dates to 1972 and housed Kmart's corporate headquarters until 2006. It is owned by the Forbes Co., which also owns the nearby Somerset Collection.

This architecturally distinct building is located at 100 W. Big Beaver Road in Troy. It dates to 1972 and housed Kmart's corporate headquarters until 2006. It is owned by the Forbes Co., which also owns the nearby Somerset Collection. The Palace of Auburn Hills: Opened in 1988 and was home to the NBA's Detroit Piston until this fall. Its last event was a Bob Seger concert on Sept. 23.

Amazon's request for proposals for cities interested in hosting the firm's second headquarters has set of a bidding frenzy across the county. The company is presently headquartered in Seattle.

Contact JC Reindl: 313-222-6631 or jcreindl@freepress.com. Follow him on Twitter @JCReindl.