Unlike most real estate developers, Bart Blatstein is a seat-of-the-pants sort of guy. If he comes up with a really cool idea in the middle of the night - Hey! Let's re-create Rome's Piazza Navona in Philadelphia! - he runs with it. Since he has an aversion to partnerships with investors and hedge funds, he doesn't have to worry about some smarty-pants business-school type telling him that his concepts sound a little far-fetched, not to mention rather expensive, and would never conform to the market's return-on-investment ratios.

The beauty of being a well-funded, independent developer like Blatstein is that you get to thumb your nose at the conventional wisdom and follow your muse. The downside is that your muse could take you down a dark alley where Disneyfied monsters lurk.

Blatstein's newest development, The Piazza at Schmidt's, on Second Street in Northern Liberties, really is modeled on the Piazza Navona, and it really does include a vast public square, paved in the exact same scallop pattern as the one in Rome.

The evidence might lead to the assumption that The Piazza is a cheap, cringe-worthy theme park. In reality, The Piazza, which opens this weekend, is anything but. Actually, it's pretty wonderful.

Eight years and $100 million in the making, Blatstein's Piazza is a massive, right-brain assemblage of apartments, offices, shops, and restaurants, all set around a one-acre plaza, and cleverly linked into his earlier Liberties Walk development. Maybe because the expanding territory of Bartistan ignored so many real estate conventions, The Piazza accomplishes something rarely seen in new American developments: It feels like a real place.

Of course, no one would ever confuse the project, which occupies the southern portion of what was once the mighty Schmidt's Brewery, with Rome's glorious Baroque gathering place, with its famous Bernini fountain and larger dimensions, 2.8 acres.

But does the Piazza Navona have a 40-foot, Daktoniks LED television beaming down every Phillies game, along with movie classics on Saturday nights? How about a sound stage for rock concerts? Or a diner inspired by Blatstein's childhood memories of road-trip pit stops at Howard Johnson?

In an age when everything new seems to come slickly packaged and fully focus-grouped, The Piazza is the eccentric product of one man's imagination, oddball ideas included. It helps that Blatstein, 54, had his natural predilection for kitsch largely, but not entirely, quashed by the talented architects at Erdy McHenry, who did not allow a single Roman column or pediment to infect the design.

Blatstein has been fixated on Rome for years. He once offered to re-create its Spanish Steps as part of a development proposal for Penn's Landing. Thwarted in that effort, he turned his sights on building a public plaza amid Northern Liberties' decaying brownfields.

The Piazza Navona has inspired several other urban squares, including Dilworth Plaza in front of City Hall, whose central pavilion approximates the Sant'Agnese church. Fortunately for Philadelphia, Erdy McHenry managed to convince Blatstein that it was possible to evoke the essential qualities of a Piazza Navona without rebuilding an exact copy of classical Rome.

The marriage of their uncompromising modern architecture and Blatstein's single-minded vision is what makes The Piazza such an authentic place. Blatstein laid out the three main residential buildings around the irregularly shaped plaza, while Scott Erdy and David McHenry cemented the architecture into the grizzled factory neighborhood with a worthy toughness.

Their buildings are constructed from materials that speak to the surroundings: poured concrete, concrete block, a rich brown brick, and glass. These components are lashed together with hard, thick strokes. Yet through a careful arrangement of solids and voids, the architects elevate the design above the factory-modern style that has become so prevalent in urban developments.

The nicest touch comes at the north end of the two buildings, when several concrete boxes burst out beyond the plane of the walls. Slightly curved, these escaping boxes establish the geometry for a smaller, secondary plaza that is home to a seven-story oval office tower.

The tower, which has been named The Rialto, serves as the project's exclamation point, yet it also acts as a pivot, sending pedestrians west along Liberties Walk, and into the dense rowhouse neighborhood to the west. Based on a computer model of sun glare, the tower's skin was clad in three kinds of glass - reflective, tinted, and clear - to reduce heat gain, while preserving the stunning views of the Center City skyline. The oval's slick surface also makes a nice counterpoint to the aged brick on the furniture warehouse that encloses The Piazza on the south.

Given that Blatstein had a falling-out with the architects near the end of construction, it's amazing how much integrity the architecture retains. He has broken with his architects on nearly every project.

But being a visionary doesn't guarantee good sense or taste. You can't help noticing that the standards decline in the interiors in the rental buildings, which give them the atmosphere of a college dorm. Outside, there are a dozen cheesy details, from the cafeteria-style tables that float aimlessly in the big plaza sea to the gas-station-quality plantings around the fountain. One also has to wonder about the screaming language of the signage. Is it really necessary to welcome visitors to this generous public space with intimidating phrases like "This complex is under constant video surveillance"?

Such imperfections are at odds with the sophistication of The Piazza's marketing strategy. Blatstein is to be applauded for packing the ground floors of all his buildings with 100,000 square feet of retail space. Storefronts were included even on the building's less-traveled sides.

Since Blatstein knew it would be difficult to fill the lots with established businesses, he hired a local artist, Amber Lynn Thompson, to act as a "retail curator." Every space will be filled with an eclectic blend of merchants, dispensing wares that include magic tricks, customized skateboards, and locally designed clothing. These tenants might not make Blatstein a lot of money in the short term, but they will certainly help make The Piazza a destination.

Blatstein also intends to program the plaza space daily, using the giant television and stage. There's something a little Big Brotherish about an immense LED screen presiding permanently over a public square. But I suspect it won't faze The Piazza's target market of 20-somethings. Their generation has spent their lives jacked into screens of all dimensions.

Now that The Piazza is finished, Blatstein is starting work on a two-story retail complex facing Girard Avenue. The project, which includes a Pathmark, was designed by New York's Beyer Blinder Bell, a more buttoned-down firm than Erdy McHenry. One wonders whether the designers might lead Blatstein down a safer, more corporate path. Then again, the odds are he'd probably fire them first.