PROSPECT (AP) – An observatory atop the new Penobscot Narrows Bridge opened Monday, giving the public 360-degree views of the Penobscot Bay islands, the Penobscot River and surrounding towns.

The glassed-in observation deck, which is 420 feet high, is part of the $84 million bridge that crosses the Penobscot River between Prospect and Verona Island. The bridge, which replaced the deteriorating Waldo-Hancock Bridge, opened to motorists in December.

The observatory is touted as a tourist attraction that will offer views as distant as Mount Katahdin. It is billed as the only observatory atop a bridge in the Western Hemisphere and one of only four worldwide – the others being in China, Thailand and Slovakia.

Even with low clouds and fog that diminished the views, the observatory drew rave reviews on Saturday and Sunday from hundreds of people who had free tickets to get preview tours.

“I think it’s magnificent. It’s beautiful. I think it’s going to be the best view on the coast of Maine,” said Kristi Blair of Orland, suggesting it topped the views from Mount Battie in Camden and Cadillac Mountain in Acadia National Park.

Department of Transportation David Cole said the observatory provides a tie-in to Fort Knox state park, where visitors park to gain access to the observatory. Cole said he could imagine visitors touring the fort, having a picnic lunch and then ascending to the observatory. The cost of admission to the observatory and Fort Knox is $5 for adults and $3 for children.

The bridge is projected to last 150 years, Cole said, so “when people are flying around like the Jetsons in 150 years, they’re going to be looking down at this bridge.”

“No, it’s not going to be Disney World, but this is going to be something we’re going to be proud of for a long, long time,” he said.

The bridge is open to the public from 9 a.m. to 5 p.m. seven days a week.