The year it turned 100, Cleveland was a town that hadn't aged particularly well.

Former Planning Director Hunter Morrison described Cleveland in 1896 as "a dirty, slum-filled industrial city."

That was about to change.

By 1912, Cleveland was poised to embark upon a decade of progress that, when viewed through the long lens of history, is so astonishing it almost defies imagination.

Tom L. Johnson laid the city's groundwork in the early years of the 20th century. Cleveland's most worshiped mayor lowered streetcar fares, built a municipal electric system, initiated the Mall Plan that changed the face of downtown, opened new parks throughout the city, and ran a Progressive-era government whose sole purpose was to improve the quality of life for its residents.

When Johnson left office in 1909, Cleveland was on the brink of greatness.

Three years later, it arrived.

And there to usher it in was Mayor Newton D. Baker, the only mayor worthy of mention in the same breath with his mentor and friend, Johnson.

Case Western Reserve University's John Grabowski is the city's pre-eminent living historian. Not one to toss about superlatives, Grabowski speaks with a sense of awe about the 10-year period that began here exactly 100 years ago.

"It was just an unbelievable decade," said Grabowski. "It was one of those times when everything came together."

By 1912, Cleveland was a city with significant wealth. And those who had it -- prodded by those who governed -- were about to put it to good use.

The decade beginning in 1912 gave birth to institutions that, a century later, remain the region's most precious assets:

• The West Side Market, designated by the American Planning Association as one of the nation's "10 Great Public Places," opened its doors Nov. 2, 1912. A million customers a year still shop there.

• The Cleveland Foundation is the city's version of a gift that keeps on giving, the world's oldest community foundation, with nearly $2 billion in assets. It was founded in 1914 by banker Frederick Goff as a vehicle to pool the resources of Cleveland's philanthropists and distribute that wealth indefinitely to projects that benefit the city. In 2011, the foundation's grants totaled $80 million.

• The Cleveland Museum of Art, one of the nation's finest, opened to the public three years after gifts and bequests from a small group of wealthy Clevelanders led to the 1913 incorporation of an art museum. A $350 million expansion and renovation of the museum is scheduled for completion next year.

• The Cleveland Orchestra, founded by Adella Prentiss Hughes, played its first concert in Grays Armory on Dec. 11, 1918. Less than three decades later, it ranked amongst the world's finest -- a position it retains today. Severance Hall opened in 1931.

• The Cleveland Clinic owes its origins to George Crile and three of his colleagues who, returning home after service in a medical unit during World War I, founded a medical practice and gave it that name. In 1921, the Clinic's first building opened on Euclid Avenue and East 93rd Street. Today, the Clinic is one of the world's largest and most respected medical centers.

• City Hall and the Courthouse opened during the decade, and a voter-approved bond issue paved the way for construction of the Cleveland Public Library, fulfilling the vision of the Mall Plan.

• William Stinchcomb founded the Metroparks in 1917.

• "Fifth City" was the nickname bestowed on Cleveland after the 1920 census, a reference to its standing as the nation's fifth-largest, behind only New York, Chicago, Philadelphia and Detroit.

How could all of this happen within the span of a decade?

Morrison attributes it to the political leadership of Johnson and Baker, and "a civic establishment that decided Cleveland should become something really special."

Grabowski agreed, adding that the city's leaders at the time also "made rational use of great wealth."

In a must-read piece written for Teaching Cleveland, a website dedicated to the city's history, Grabowski argues that 1912 may have been the year "Cleveland became a modern city, one deserving of national emulation."

A century later, a new young leader walked through the West Side Market early one recent morning, talking about the upcoming 100-year celebrations of places -- like the market -- "that made this city so special."

But Eric Wobser, head of Ohio City Inc., added the centennials must also challenge Cleveland's leaders "to use these institutions, these cultural treasures, as drivers for the next 100 years."

Those treasures have aged well. Other parts of the city have not.

The challenge ahead is to become more like the Cleveland that grew out of 1912, and less like the one of 1896.

Larkin was The Plain Dealer's editorial director from 1991 until his retirement in 2009.