As the Greek philosopher Plato once noted, "He was a wise man who invented beer."

Historians, however, aren’t sure who first made beer — or even where it originated. For certain, it is one of the first beverages humans ever produced.

Wikipedia suggests that beer dates back to at least the fifth millennium B.C., served up in ancient Egypt and Mesopotamia. This corresponds roughly with the first domestication of cereal essential to the fermentation process necessary to make beer. It also notes beer was known in Neolithic Europe as far back as 5,000 years ago.

With the Industrial Revolution, the production of beer advanced from artisanal methods to industrial-scale manufacture. As we all know, the industry has grown into a huge global business with more than 35 billion gallons of beer sold annually, producing revenues estimated at nearly $300 billion.

The Beer Institute reports that Americans drank an estimated 6.3 billion gallons of beer last year an average of 28.3 gallons per person but also noted that beer consumption has declined slightly over the last several years.

Market Watch's Quentin Fottrell says the reason for the decline can probably be attributed to the fact that baby boomers and retirees, the highest beer-consuming segment, aren't drinking as much as they did when they were younger. Another factor, he says, is that the drinking habits of young adults are changing, trending toward wine and spirits.

There is, however, one notable exception to the decline. Craft beer, produced by a growing number of microbreweries and brew pubs, has made substantial gains in recent years.

There are nearly 3,000 breweries in the U.S. today. Most are microsized operations, led by creative entrepreneurs who focus on local styles and flavors, introducing new brands at a rapid pace more than a thousand last year alone and many at higher prices than standard brews.

There are a number of hot spots around the country cities where craft beer has really taken hold and as a result media attention to this phenomenon has mushroomed. A host of major media outlets, including CNN, USA Today, Esquire, Travel & Leisure, Oyster.com and even the Wine Enthusiast, have rushed to name the nation's "Best Beer Cities."

Rather than taking a me-too approach, I decided to put the various "Best Beer Cities" lists through some statistical analysis to see if we could come up with a consensus list that would more accurately rate the half-dozen top beer cities across the country. So here's what our sudsy study revealed.

1. Portland, Oregon

No doubt about it, Oregon's largest metropolis should change its nickname from the "City of Roses" to "City of Beers." Or maybe the "Hub for Hops" as suggested by Travel & Leisure's Katrina Brown Hunt. Fact is, nearly every survey we encountered named Portland as the best city for beer in the nation. Some say the world.

Portland does boast the highest concentration of breweries 76 in the metro area of any city on the planet. Deschutes Brewery, Upright Brewing, Hopworks Urban Brewery, Cascade Brewing and Commons Brewery are perennial favorites in this quirky hipster-oriented, beer-loving city.

2. Denver, Colorado

With a long-standing reputation for producing some of the nation's best brews, the Mile High City earned a solid second place in our analysis of beer city ratings. The city's first craft brewery, Wynkoop, was opened in 1988 by John Hickenlooper, who went on to become mayor and then governor of Colorado. Wynkoop remains a favorite, along with Great Divide Brewing, Denver Beer Co., Blue Moon Brewing Co., Bull & Bush and Falling Rock Taphouse.

Denver also stages the largest and most prestigious beer festival in the country the annual Great American Beer Festival, next up Sept. 24-26, 2015.

3. Philadelphia, Pennsylvania

The City of Brotherly Love certainly loves its beer. Beer-filled taverns have been a mainstay since Philly's founding, so an appropriate place to start the night here is at McGillin's Olde Ale House, the city's oldest tavern (dating back to the mid 1800s).

Less ancient brewers, including Victory, Sly Fox, Philadelphia Brewing, Nodding Head, Yards Brewing Company and the new City Tap House are contemporary vanguards of the local brewing scene. Pilsners have always been the name of the game in Philly, and Esquire's Evan S. Benn names Victory's Prima Pils "the best pilsner in the nation."

Philly Beer Week set for May 30-June 8, 2015 celebrates the city's vibrant beer culture and is said to be quite a hoppening event.

4. Boston, Massachusetts

Boston's first brewery emerged shortly after the Pilgrims dropped anchor there in the 1600s, lending plenty of historical credence to the city's title as America's original beer town. According to CNN, Boston also rates tops in the country for per-capita beer consumption.

Fueling that thirst is a host of breweries, including the best-selling craft brewery in America, Boston Beer Co., producer of Samuel Adams. It's a juggernaut nowadays, but many small breweries have followed in its wake, including Harpoon Brewery, Boston Beer Works, Trillium, Cambridge and Cape Ann Brewing Co.

Like other leading beer cities, Boston has its annual beer festival the American Craft Beer Fest the East Coast's largest celebration of domestic micros, upcoming May 29-30, 2015.

5. San Diego, California

As host to the 2012 World Beer Cup the so-called "Olympics of Beer Competitions" San Diego cemented its position among the country's leading beer cities.

Sprawling San Diego County is sprinkled with several dozen innovative and highly respected craft breweries, including Ballast Point, Green Flash, Lost Abbey and Karl Strauss Most famous of all is Stone Brewing Co., declared by BeerAdvocate magazine the "All-time Top Brewery on Planet Earth."

6. San Francisco, California

The City by the Bay has some serious beer cred and plenty of history, too beginning with Anchor Steam Brewery, the oldest craft brewery still in operation in the U.S., dating back to 1896. Some 40 micro and "nanobreweries" have followed suit around the Bay Area, led by New Albion Brewing in Sonoma, the first new brewery in California following Prohibition.

More recent additions include the aptly named 21st Amendment Brewery, Speakeasy, Black Diamond and Drake. Notable too are such innovators as Almanac, Moonlight Brewing Company and Cerveceria de MateVeza that have been experimenting with food-inspired brews adding infusions of herbs, seasonal produce and even tree bark to their beers for cutting edge flavors.

Rounding out our consensus top-10 best beer cities are:

  • Chicago, Illinois
  • Austin, Texas
  • Seattle, Washington
  • Burlington, Vermont

With the craft beer craze sweeping the nation, there are, of course, many other notable beer cities. Here are some of them (listed alphabetically):

  • Asheville, North Carolina
  • Atlanta, Georgia
  • Bend, Oregon
  • Brooklyn, New York
  • Kansas City, Missouri
  • Milwaukee, Wisconsin
  • Minneapolis/St. Paul, Minnesota
  • Portland, Maine
  • Santa Rosa, California
  • St. Louis, Missouri

If you're a malt-maven, be sure to make note of these cities when planning your next "beercation."