Philadelphia is a city where the streets are paved in gold, as well as occasionally in hues of blue, red, and orange. We are talking bricks, and there is probably no place in America that can boast such a rainbow of paving colors, materials, and textures. You can find dozens of streets surfaced in Belgian block, cobblestone, riverstone, and bluestone.

There is even one spectacular street paved in oak blocks.

Or, rather, it was paved. Philadelphia's last intact wooden street has abruptly gone undercover.

A relic from the days of carts and horses, those wooden pavers now lie hidden beneath an asphalt surface on the 200 block of South Camac, the atmospheric alley of private clubs secreted between 12th and 13th Streets in Center City. Although Camac's wooden blocks are considered important enough to be listed on the city's Historic Register, their landmark status couldn't prevent bad things from happening to them.

The century-old wooden street underwent a major reconstruction in 2012, but almost as soon as the city finished its work, the new pavers began to rot. Some dissolved into pulp, others began to pop out of place. Fearing the street was becoming a hazard to pedestrians, the Streets Department decided last month to embalm the 200 block in asphalt, at least temporarily.

At a time when Philadelphia churches and theaters seem to vanish every week to make way for new development, it is especially painful to see a place so rare and unique disappear before our eyes.  Just a few months ago, the city paved over a century-old - but not designated - wooden street accidentally unearthed during the demolition of Mount Sinai Hospital in South Philadelphia. Fortunately, in the Camac case, the treatment is expected to be reversed.

Streets Commissioner David Perri has assured Camac Street's tenants that his department is committed to a faithful restoration of the distinctive wooden pavement. And, in an interview, he confirmed the work has been scheduled for 2016. The challenge will be to figure out what went wrong with the 2012 reconstruction, said Perri, who will move to the Department of Licenses and Inspections after Jim Kenney is sworn in as mayor.

The narrow Camac alley, home to such venerable institutions as the Franklin Inn Club, was first paved with wood blocks around 1917, as a way of quieting the noisy clip-clop of horses and wagons. Those first blocks lasted for decades. A 1998 replacement also stood up pretty well.

But when new pavers were installed in 2012, the street became a sponge that trapped water, destroying the wood. Perri now believes the drainage was inadequate. This time, the department plans to use larger blocks - perhaps in a different wood, such as hard yellow pine or black locust - and pressure-treat the material.

Given the city's never-ending struggle to keep its ordinary asphalt streets from crumbling, it's admirable that Perri is focusing so much effort on tiny Camac Street. An engineer, Perri concedes he has a soft spot for the city's quirky old paving systems. This is a good thing because the Streets commissioner is also the official steward of the Philadelphia Historic Street Paving Thematic District.

Yes, there is a historic district to protect street pavers, just as there are historic districts for the city's architecturally distinguished neighborhoods. It covers 260 blocks scattered throughout the city.

Did you know, for instance, that Germantown and Manayunk are full of yellow-brick roads? Or that Old City and Queen Village were partial to a blue-glazed brick? It's common to see redbrick sidewalks in Philadelphia. But there also are whole streets slathered in red, including the 700 block of Sansom, the main street of the Jewelry District.

Pavers aren't merely a curiosity. It turns out you can pretty much trace the origins of municipal government to the evolution of paving technology, according to the mission statement that established Philadelphia's historic paving district.

Because building streets was always expensive, individuals had to band together to organize their construction and oversee their maintenance. The smooth surfaces made it easier and faster for people to bring goods to market. People grew wealthier, and everyone benefited. That collective effort evolved into our first formal governments. When you think about it, the need for infrastructure is really the foundation of modern society, a fact the antitax crowd often forgets.

Though wood blocks, like the kind used on Camac Street, may look primitive, they aren't the oldest paving treatment. The Romans and others commonly used river stones to surface their streets. Large cobblestones came later. It wasn't until the Civil War that improvements in stonecutting technology made square Belgian blocks the standard for street paving.

Stone paving kept city streets from becoming muddy rivers, but it also accentuated the noise from horses and wagons. In 1910, an inventor named Samuel Nicolson came up with an alternative. He began selling wood blocks from the end grain of wood, like butcher block, because they could withstand more weight than the traditional cut. Nicolson also had the blocks soaked in creosote, the same foul-smelling preservative used on railroad ties, to prevent rot.

Nicolson's wooden blocks quickly became a popular alternative to noisy cobblestone and Belgian block, especially on streets near hospitals and schools, and on narrow alleys where the sound reverberated. But it wasn't long before people became fed up with the smell of the toxic creosote, even though it helped the wood last longer. By the 1920s, inventors were offering a better product: asphalt.

Today, there are only a handful of wooden streets remaining in American cities. St. Louis has one. So does Pittsburgh.

The miracle is that Camac's wooden blocks survived amid the tumultuous changes of the last century, as the surrounding neighborhood shifted from an area for the very wealthy, to one for the very poor, to the center of the Gayborhood. Today, there are major apartment projects at either end of the 200 block.

And, with a little luck, those wooden pavers will be looking as good as new in time for the street's centenary in 2017.