EXCEPT FOR wedding planners going gaga over its Gilded Age grace and birders beholding its bald eagle, the city's only public Delaware River waterfront estate is a hidden treasure on the residential streets of Torresdale in Northeast Philadelphia.

Glen Foerd - 18 acres of woodlands, wetlands, a waterfront trail and English gardens at the confluence of Poquessing Creek and the Delaware River - is open free to the public daily from dawn to dusk on Grant Avenue near Milnor Street.

Who knew?

The Glen Foerd mansion - a 19th-century vision of elegance with a grand staircase, a stained-glass dome, an art gallery and the kind of ethereal light that the Great Gatsby would have dug - is open for Saturday and Sunday guided tours through Dec. 21.

Meg Sharp Walton, the estate's executive director, wants the public to enjoy what she experiences every day - time travel.

"There are other mansions in the city," Walton said, "but this is an intact 19th-century estate with a great art collection and, I mean, it's right on the river.

"The opposite bank is undeveloped," she said. "So you stand here and look across the water and you swear you've stepped back in time. You come here and it's like an immersive experience. It's just so beautiful."

Glen Foerd sits on a bluff overlooking the Delaware, so when the river floods, the mansion and the estate don't.

The view from the bluff includes a feeling for the river's dramatic tides.

"When you're down in [Center City] Philadelphia, you don't get a sense of the Delaware River as a tidal basin," Walton said.

"But up here you do. When the tide is out, you actually see a big beach. Over the course of eight hours, the river goes from nothing at low tide to really wide at high tide. So you get a sense of this great tidal basin."

Visitors walking up the steps from the riverbank are greeted by the cast-iron dog "Little Ugly," just as the live version once greeted Glen Foerd's 19th-century owner, Charles Macalester Jr., when he came home from a day on the water.

Little Ugly's gravestone, erected after his death on July 28, 1871, lies under an ancient oak tree nearby.

It reads, "In Life a Devoted Friend, the first to welcome, the foremost to defend."

Perhaps in deference to Little Ugly, dogs on leashes are welcome year-round at Glen Foerd, but not in the mansion's 22 rooms and eight bathrooms.

People, however, can join the mansion tours at 11 a.m. and 12:30 p.m. this weekend and next. After that, it's wait until spring, right around the time when the nesting ospreys return for their ninth year on the Glen Foerd estate.