For decades, a parking garage that has towered over Eighth Street as a dank monument to urban renewal has greeted motorists as a glaring eyesore.

While revitalization failed the first time around with the Parkade, the Philadelphia Parking Authority hopes the second time will charm.

The agency best known for coldly efficient parking enforcement is behind a $28 million overhaul of the prominent garage that's surprisingly inviting.

From the inside, the behemoth that houses nearly 1,200 spots and forms a tunnel along Eighth Street in Market East has been gutted, repainted, repaved, redecked, rewired, relit - it will even have two charging ports for electric cars.

But the long-forbidding exterior is where the project truly packs civic punch.

The dour facade greeting motorists exiting the Vine Expressway is now a canvas of small glass panes - colored, frosted, and transparent - glittering or changing color while set against snow-white paint.

Spindles of LED lightbulbs now dangle from the tunnel formed by the overhead structure, illuminating a once-forgotten zone of retail stores.

From Market Street a half-block to the south, the facade is newly draped in vertical, expandable metal mesh panels, between which designers will thread live vegetation the length of the multistory garage before the project is completed next month.

Financed mostly by a 30-year bond, the project is a stretch of the PPA's primary mission. But officials high up in the $240 million agency said they were drawn by the same desire to reimagine Market East that has fueled massive private investment over the last few years.

"I know the Philadelphia Parking Authority is primarily identified with writing tickets and towing cars," said Richard Dickson, deputy executive director. "But we're actually much more complex. We looked at this as a signature project."

Center City District chief executive Paul R. Levy said the space goes beyond what private garage owners have done. "This is a very exciting project," he said.

The woman key to the makeover is Nacima Boukenna, a Penn grad who has spent 27 years at the authority waiting for such an opportunity.

"The thinking was ripe in Philadelphia," said Boukenna, the authority's engineering and design chief, who earned a master's in landscape architecture from Penn, where her mentor was a pioneer in the field, Ian McHarg. "We wanted to do something different," Boukenna said.

The idea, hatched about four years ago, was to eliminate blight, restore the garage to top condition, and set an example others could follow at other garages and dead zones in Center City.

"Wouldn't it be great," Boukenna explained, "if all these dark tunnels we have in the area could become something attractive?"

When built in 1964 by the Parking Authority, the garage was meant to rescue nearby department stores from the competitive scourge of suburban malls that had drained them of customers.

But parking spaces came at a cost, encasing Eighth Street. And even with the construction a decade later of the nearby Gallery at Market Street shopping mall, the neighborhood continued to fall into decline. The department stores closed.

Five years ago the Parking Authority regained control of the garage after a series of defunct department-store operators had held rights to it under a lease.

The garage was structurally compromised. Its street-level stores were operating, Boukenna said, "in absolutely deplorable conditions."

The stores beneath the garage have been gutted and repopulated, though with only a few tenants so far, including a dry cleaner, shoe repair shop, and convenience store. A portion of those spots will go for Parking Authority customer offices that were lost when the agency moved from its University City digs into the former Lit Bros. building next door.

Dickson said the loan for Parkade will be paid with mostly future garage revenue. Meanwhile, reviews are underway of all the Center City garages the Parking Authority owns, underground at Independence Mall, Second and Sansom Streets, Ninth and Filbert, and 10th and Ludlow.

One of the designers on the project, Joseph W. Healy of Philadelphia-based WRT, said a movement is afoot to view urban garages as more than just parking warehouses.

"Garages are [increasingly] seen as a part of urban infrastructure that can be used to define public space," said Healy.