The bidding for the former Charleston Naval Hospital is heating up as the federal government's effort to sell the shuttered landmark building winds down.

The top offer, submitted just before 3:30 p.m. Friday, was $1,787,878. At least three bids of more than $1.5 milion were registered Friday.

The U.S. General Services Administration, the agency that disposes of the government's excess real estate, is trying to unload the boxy, 10-story structure and the surrounding land through an online auction.

The bidding for the 24-acre site at 3800 Rivers Ave. opened at $100,000 on Sept. 13.

The auction has drawn five participants, the sales website showed.

The would-be buyers, who had to put down $50,000 each, were not identified. The city of North Charleston placed an early bid but does not expect to buy the building, said spokesman Ryan Johnson.

“We're not going to be purchasing it.” he said Friday.

If the government accepts the top bid, the buyer will get title to the 368,000-square-foot main building, the three-story former enlisted quarters, tennis and basketball courts, and parking for about 900 vehicles,

The auction, which was supposed to end Thursday, has been extended until at least today. Final offers are due by 3:30 p.m., though the window could stay open until Tuesday or even later, according to the website.

The 175-bed hospital at Rivers and McMillan avenues was the fifth that the Navy built over the course of more than seven decades to support the Charleston Naval Base and Shipyard.

It opened in 1973 and employed more than 1,200 health care workers before the Navy decided in the early 1990s to close the adjoining base and shipyard.

As patient numbers waned, the Pentagon gradually shut down portions of the hospital, which was a walk-in clinic when it was closed for good two years ago. At the same time, the Navy began offering health services at a newly built medical center on the Naval Weapons Station.

The vacant hospital is in a blighted area that private developers and North Charleston officials have struggled to revitalize. For example, the city bought the old Shipwatch Square shopping center across Rivers Avenue from the hospital for $2.5 million in 2010, but it hasn't yet been able to attract a full-service grocery store to the cleared site.

While North Charleston isn't a player in the hospital auction, the building remains a critical piece of real estate, Johnson said.

“It is, especially being across from Shipwatch Square,” he said. “We've had a huge interest in that corridor. It would be a key component of the revitalization of the southern end of the city.”

Contact John McDermott at 937-5572.

Editor's note: This story was updated Oct. 8 to include the fact that the city of North Charleston was one of the five bidders.