When the owners of the New York Yankees decided their team needed a new ballpark, they went out and built themselves a monument, an imposing structure in size and scope.

That was in 1923.

Eighty-six years later, they've done it again.

At a cost of about $1.5 billion, considerably more than the $2.5 million price tag of their first home, the team plays its first regular-season game April 16 in new Yankee Stadium, built in the shadow of the original stadium and — like its predecessor — meant to awe.

Eight miles away, in Queens, the Mets have their own new home. Built for about half the price of Yankee Stadium, Citi Field is more cozy than corporate, a ballpark with a deliberately old-time feel.

In each case, nostalgia was a major architectural ingredient. The new homes of New York's major leaguers both, in their own ways, try to create a feel of walking into famous ballparks of decades past.

The irony is that those stadiums weren't always so great — though it's also hard to argue that luxury should trump atmosphere.

When the Mets joined the National League in 1962, they played at the Polo Grounds, a rickety ballpark on its last legs. The original Polo Grounds opened for business in 1880 and the one the Mets used was its fourth incarnation, constructed in 1911.

A quirky, horseshoe-shaped place, it had acres of ground in center field but short foul lines to left and right field. That led to 257-foot pop fly home runs down the lines and 450-foot fly ball outs. The bullpens were in fair territory in deep left and right fields, with quaint roofs hanging over the benches. The clubhouses were even farther out.

The ballpark's most memorable moment was Bobby Thomson's pennant-winning home run in 1951 for the New York Giants. But the team couldn't even sell out the building for that season-defining game, an ominous indication of what was ahead — relocation to San Francisco.

Ambitious promoters tried to introduce a college bowl game to the building as it was nearing the end of its life span. Place-kicker Jim Turner played in the Gotham Bowl and recalled the experience ruefully. "There were more pigeons than people," Turner said. "It was a dump. It had seen its day."

The city's other now-departed team, the Brooklyn Dodgers, played at Ebbets Field.

It was a bandbox of a ballpark, so intimate fans felt they could shake hands with the players. The outfield fences carried advertisements, including a homespun one in right field that said: "Hit Sign, Win Suit." If the Dodgers right fielder protected the wall all season, sponsor Abe Stark, a clothier, doubled the payoff with two suits.

Opening in 1913, the Dodgers' home had a carnival atmosphere with superfan Hilda Chester clanging a cowbell and the Dodgers Sym-phony, a sort of pep band dressed as bums, serenading the fans. One time, an apparently enraged fan hopped on to the field and attacked an umpire. That distracted the crowd, allowing his pickpocket partner to operate uninhibited in the grandstand.

There was a rotunda at Ebbets that served as a meeting place for customers and it's no accident that Citi Field, with its replica twice the size of the original, looks so much like its ancestor. That's because Ebbets was where Brooklyn-born Mets owner Fred Wilpon grew up and when it came time to replace Shea, he built a reincarnation of the field of his boyhood dreams, a sort of Ebbets Field redux.

Both ballparks are long gone now, replaced by housing projects. And what's left of Shea Stadium, the Mets' sterile home from 1964 through last season, has been reduced to a pile of rubble that is being removed and replaced by a parking lot next to Citi Field.

Up in the Bronx, the old stadium was meant to be intimidating but baseball was the focus.

In the new one, the games are almost an afterthought in an ostentatious palace that includes more than a dozen restaurants, bars, lounges and cafes, segregated by seat price, plus specialty food courts. There's a Lobel's for high-end steaks, and a Peter Max art gallery, with originals for sale. It is a tribute to excess, a palatial baseball palace, heavy on panache.

The trademark lattice facade returns to the rooftop and Monument Park, which honors the heroes who turned the Yankees into one of the most successful franchises in all of sports, stands beyond the center-field fence. There's also a Yankee museum and, it seems, a place to buy team gear everywhere you turn.

Much has been made about the obstructed views in the new stadium's $5 bleacher seats, which were blocked to accommodate a sports bar.

But the original stadium had its own obstructed views. Built with 1920s architecture, the place included pillars all around the park, leaving fans peeking around them for a glimpse at the action. And that included the premium seats located from baseline to baseline.

Somehow, though, fans in those days never minded playing peek-a-boo with the game on the field. No one ever thought of a Yankee Stadium without those poles dotting the landscape.

Then, when the ballpark was redone 35 years ago, the pillars somehow disappeared.

That was progress in the 1970s.

In the 21st century, progress is a sports bar behind tinted glass.