For all the monumentality of the old 30th Street post office, Philadelphia would be better off had it been located in some less-visible corner of the city. Armored in a quarry's worth of limestone, the full-block building lords over the Schuylkill like a medieval fortress. Its main charm was the lavish art deco retail store on the ground floor. But now that the Internal Revenue Service has moved its regional headquarters there, even that space is off-limits to the public for security reasons.

In spite of those unfortunate qualities, the IRS's new, $252 million offices are being heralded by city poobahs as a great new gateway to University City, the connective tissue that will bind Philadelphia's east and west banks into one, job-generating unit. The word gateway was uttered so many times at last week's dedication, it sounded like a form of denial.

The post office, designed by Rankin & Kellogg during the Great Depression, was an urban barrier in the past, and it is an even bigger barrier now that it has been ringed with security posts and twinned with an off-putting parking garage. Uniting the two sides of the Schuylkill is a worthy planning goal, but a high-security facility cannot possibly serve as a gateway to anything.

I'll concede that the city is better off having this enormous bunker filled with 5,000 IRS employees than having it sit empty. But who said those were Philadelphia's only choices? The University of Pennsylvania, which bought the property from the U.S. Postal Service, had explored several intriguing uses, including research labs and a shopping mall, before flipping the building and an adjacent site in 2007 to Brandywine Realty Trust, developer of the iceberg-shaped Cira tower nearby.

Brandywine knew that the IRS would need a high level of security at its new home, which was renovated by Bohlin Cywinski Jackson. While hardly unreasonable, the agency took safety to an extreme. The installation of blast-proof windows on the upper floors makes sense. But the decision to ban public uses at street level feels like overkill and is a loss for the gateway cause.

As part of the security mania, the IRS also resorted to the most knee-jerk of safeguards: a stockade of poles around the perimeter. For years, designers have shown that you can get the same protection with an attractive mix of concrete benches and planters. The IRS also had an outdoor dining porch on 30th Street - the former truck dock - encased behind a metal fence. Those harsh-looking barricades make you wonder whether locating federal offices in downtowns now does cities more harm than good.

The sad part is that 5,000 IRS jobs don't even constitute a net gain for the city as a whole. The agency relocated from Roosevelt Boulevard after the post office's 3,000 workers left Center City for a modern processing facility at Philadelphia's airport.

One advantage of the IRS move is that it provides Brandywine and its partner, the Keating Group, with a reliable tenant in the center of a much larger development. Back in 2007, Brandywine released a dazzling master plan for the area by Pelli Clarke Pelli, which designed Cira. The renderings show two diamond-cut, Cira-like towers sprouting south of the post office. They flank a dynamic-looking garage camouflaged with folded mesh screens and a dot matrix of LEDs.

The prospect of so much density and human activity was exciting, and it was possible to imagine a second Center City on the west bank of the Schuylkill.

To see the site today is to marvel at the bait-and-switch.

There are no soaring towers next to the IRS building, just two vacant building lots. Their absence, of course, can be excused by the recession. It is harder to give a pass to the disappointing garage, especially when 30th Street Station - the heart of the regional transit system - is right across the street from the IRS and makes it easy for workers to leave their cars home.

There may be a few places where a nine-level garage makes sense, but the riverfront is not one of them. This 1,662-car structure, which the IRS demanded as a condition of its lease, is the second on the river since Amtrak's went up next to Cira. To think, Penn's own master plan calls for yet another riverfront garage a few blocks south.

The IRS garage, a joint effort by Blue Bell's Tim Haahs and New Haven's Pelli, is a raw, cast-concrete affair with visibly open decks facing Center City. In place of the promised mesh and LEDs, there is a stainless-steel stripe and charcoal panels to relieve the tedium.

Brandywine's chief, Jerry Sweeney, deserves credit, however, for holding the line on the IRS's demands for an even larger garage, and for resisting its request for a connecting bridge to the post office that would have enabled employees to avoid ever stepping onto a Philadelphia street.

Sweeney also included a row of retail spaces on the 30th Street side of the garage. They give an inkling of how Brandywine's master plan might help the area evolve into more of a real urban place. Once Penn's new riverfront park opens this summer, pedestrians may venture down 30th Street between the green space and the station.

The challenge now will be to make something of the highway-like section of Market Street that separates the IRS from the train station. PennDot is supposed to start work this month on two, 40-foot-wide plazas on either side of Market.

If things work out, the University City District will set up tables, chairs, potted plants, and maybe a farmers market at this time next year. These improvements would narrow Market Street and make the entrance to University City feel more welcoming.

Then, maybe, we can start calling it a gateway.