Order a beer at a restaurant or bar, and unless you've requested an ale, porter or stout, you'll probably be served the clear, golden brew behind our most familiar brands: Pilsner.

And this is its ancestral home.

Mugs of frothy beer served in this cobblestone-studded city southwest of Prague may resemble others the world over, but a trip to the local brewery confirms these are no ordinary suds.

The faintly bitter lager first produced in Plzen more than a century ago gave rise to a style of beer that has since circled the globe. Much of today's lager-style beer, in fact, owes its flaxen color and crisp flavor to a brewing process formulated in this small metropolis in the Czech Republic's Bohemia region. Its name still reflects its origins: Pilsner, Pilsener, or sometimes just Pils.

The beer's precise birthplace, the Pilsner Urquell brewery, stands on the city's fringes, enclosed by an ornate 19th century double archway. Its copper kettle-lined confines have changed with the times, but visitors can still see hints of the past, including a network of underground tunnels once used to store huge casks of fermenting beer.

The plant's distinctive heritage hasn't been overlooked by its current owner, London-based SABMiller, which has built a large diorama of an old-time brewery inside a sleek visitors' center also furnished with a vending machine that dispenses beer.

The Pilsner Urquell factory of today is a marvel of modern brewing, operating 24 hours a day and churning out 120,000 bottles of beer per hour. But it has its origins in a brewing tradition that stretches back to the late 1200s, when King Wenceslaus II granted brewing licenses to more than 250 city residents. But the quality of Plzen's beer was poor, according to the brewery, and in 1839 protesters dumped 36 barrels of the local brew outside the town hall to show their discontent.

Click here for more info on Plzen from Professional Travel Guide

That prompted the citizen brewers of Plzen to combine forces and build a modern beer-making facility, which opened in 1842, the same one that operates to this day.

A young brewmaster and reputed ruffian, Josef Groll, took the helm and began making the beer that became known as Pilsner lager, fermenting barley malt, hops and water at a low temperature, and adding yeast that collected at the bottom of the mixture.

Among the beer's defining qualities were its shimmering appearance and subtle bitterness from locally grown hops - the dried flowers of the hop plant. Other ingredients specific to the region included soft water drawn from 328-foot-deep wells and malt made from barley grown in the Czech regions of Bohemia and Moravia.

The water used in today's Pilsner Urquell, the company says, is from the same underground source used to make the original in 1842. And the strain of yeast used to convert sugar into alcohol during the fermentation process reputedly is traceable to that used in the original recipe.

The brewing of Pilsner Urquell has remained largely unchanged since Groll's time, according to a video shown to tourists at the brewery. Ground malt and water are boiled three times in copper kettles, a procedure carried out perhaps once or twice in the making of other beers. Carmelization occurs at the bottom of the kettles, producing flavorful compounds.

The concoction is boiled with hops before being fermented at a low temperature, pasteurized and packaged in bottles, cans, kegs and tanks. The total brewing time remains the same as in the days of yore, about five weeks.

Julie Johnson, editor of All About Beer magazine in Durham, N.C., noted that the beer's name, Urquell, means "the original source" in German.

"Pilsner beer is the ancestor of the kind of global international lager style that makes up 90-something percent of the beer we drink today," she said, pointing to brands such as Budweiser, Rolling Rock and St. Pauli Girl. "Those are all indebted to Pilsner."

In a nod to the beer born in Plzen, American brewers of the 19th century created "something that was much softer for the American palate," she said. "That, in turn, has swept the world."

Pilsner, and pale ales that emerged around the same time, stood out because "they were light, they were beautiful to look at," Johnson said.

The beers owed their attractive look to malt made from barley that had been heated evenly using an indirect source - then a revolutionary technique. Earlier malt may have been partly burned, producing beer with "a darker and roastier taste," she said.

The malt's consistent quality yielded exceptionally clear beer, and its emergence coincided with the spread of glassware that allowed drinkers to admire its appearance.

"So you had a beer that appealed to the eye as well as the nose and mouth," Johnson said, "and people were just struck dumb by how lovely and beautiful it was."

Pilsner Urquell's flavor, which is dry rather than fruity like an ale, comes from local ingredients such as the locally grown hops, known as Saaz hops, she added.

Visitors to the brewery can sample that flavor at the end of a guided tour that last about an hour and-a-half and ends in one of the underground cellars used to store barrels of fermenting beer in the days before refrigeration.

One guide, Katerina Sedlackova, attested to the qualities of Plzen's namesake beer, offering cups of the drink - freshly made, unpasteurized and drawn from one of a few remaining wooden barrels kept in service.

"You should know that Pilsner Urquell is very healthy," she exhorts, referring to nutrients such as vitamin B. "If you drink a cup of beer a day, you should stay healthy."


If You Go...

PILSNER URQUELL: http://www.pilsner-urquell.com/. Brewery: http://www.prazdroj.cz/en/ or 011-420-377-062-888.

PLZEN, CZECH REPUBLIC: Official site of Plzen: http://www.plzen.eu/en/home/index.html

BREWERY TOURS: 10:30 a.m., 12:30 p.m., 2 p.m. and 4 p.m. daily May-September (no 10:30 a.m. tours October-April). Tickets are about $6.50 (130 Czech Korunas). Brewery also has a restaurant and gift shop.

A separate museum at the site of a former licensed brewing house in Plzen is open daily, 10 a.m.-6 p.m., April-December (10 a.m.-5 p.m., January-March). Phone: 011-420-377-235-574. GETTING THERE: Plzen, the Czech Republic's fourth-largest city with a population of 170,000, is about 55 miles southwest of Prague. From Prague, the train takes about two hours, tickets about $10 (210 Czech Korunas). By bus, up to 90 minutes, about $4 (80 Czech Korunas).

Click here for more travel info from FOXNews.com Travel