The Democratic Convention will be held in Boston in the summer of 2004. Is that a bad idea?

Not at all. If the American left is to redefine a set of values that can attract a majority of voters in a presidential election sometime in the next eight or twelve years, Boston is the right place to start.

Probably not since Pittsburgh cleaned itself up in the 1950s and 1960s has an American city made such a success of itself as Boston in the 1980s and 1990s.

To be sure, the Massachusetts capital was insufferably smug in colonial days, much as New York is today. Until the Erie Canal in the 1840s opened the enormous internal market of New York State to the sea, Boston was America’s most important city. (Quaker Philadelphia waxed and waned but projected little force.) Some of the Commonwealth’s ingrained preachiness has lingered on.

But time has humbled Boston, dissolved many of its pretensions and revealed the sturdy arrangements by which it is constructed underneath. Today, the city is full of symbols.

To begin with, there is the strong Democratic Party mayor who earlier this month won the convention for Boston after a years-long competition with several other cities. Former city councilor Thomas F. Menino originally billed himself as an “urban mechanic,” capable but modest in his ambition for City Hall.

Now midway through his third four-year term, Menino probably has earned the right to be described as an urban visionary, not for any single thing he did but for the coherence of what he has achieved. He took advantage of boom times to arrange a continual upgrading of the infrastructure of the city, beginning with his determined efforts to stem the flight from a public school system greatly damaged by mandated busing.

Come convention-time, Menino will have something concrete to show off — plenty concrete. Boston’s  “Big Dig,” symbolized by an elegant new cable-stayed bridge over the Charles River at the city’s northern gateway, will have mostly opened.

The federally-funded project to dig a tunnel for the interstate highway that for 40 years has cut in half the city’s oldest sections has been widely interpreted around the country as political pork, plain-and-simple. The project was in fact a Democratic Congress’s parting gift to House Speaker Thomas P. “Tip” O’Neill.

But the fact is that the elevated highway was one of the first segments of the interstate highway system to open — and the last one to be paid for entirely by local funds. Immediately after its completion, Massachusetts began paying its 4-cents-a-gallon gas tax into the federal Highway Trust, contributing to the financing of superhighways from Texas to California.

Massachusetts’ turn finally came after thirty years. The result is, for the most part, a remarkable success.

The tunnel and its various extensions have been rated the most sophisticated civil engineering project ever undertaken by Thomas P. Hughes, dean of American historians of technology. Hughes’ chapter on the artery project in his wonderful little book Rescuing Prometheus remains the best introduction to it. (Hughes’ other three monumental projects that “changed the modern world:” the SAGE missile defense system, the Atlas intercontinental ballistic missile system and ARPANET, precursor to the Internet.)

The central artery project was undertaken by the same firms that built earlier San Francisco’s Bay Area Rapid Transit (BART) System. Bechtel Corp and Parsons Brinckerhof Quade & Douglas undertook construction the only way they could — beneath the existing system.

One day in 2004 a switch will be flipped (metaphorically speaking.) The tunnel will open. The skyway will close. It will then be torn down and replaced by structures and open spaces that have yet to be determined. For the past eight years, traffic has moved along the elevated highway, relatively little-disrupted, though sometimes surprisingly redirected.

The Big Dig’s real impact on the city has less to do with relieving the traffic congestion that has plagued it — or with the renewed cityscape above the tunnel that now will re-knit the downtown’s severed halves — than it does with the new wing that is being added to Boston’s business district as a result.

For the single most important feature of the project may be a third tunnel under Boston Harbor. In effect, the Ted William tunnel bypasses city’s downtown altogether, in order to connect the airport on harbor’s far bank with the highway system and suburban Boston. A thousand nearly empty acres separated from the downtown by a narrow channel have been opened to development as a result. They were rail yards, and dockyards and parking lots for the past hundred years

Financial service firms have been flooding into new tall office buildings built in the “seaport district,” across from an exposition pier. A huge new convention center will be open by the time the Democrats arrive. Chicago’s Pritzker family has won permission for a large new Fan Pier waterfront development at with hotels and a new museum.

Mayor Menino has pushed for plenty of upscale residential housing among the new developments, to insure the new seaport district remains active 24-hours a day. At the same time, he has plumped for controls to slow the rise in rents in the rest of the city has been experiencing — a more traditional Democratic Party policy response.

There is no better symbol of the Boston renaissance than the Federal courthouse that now holds down a corner of the new neighborhood facing the financial district. Across the water on the city-side is the celebrated building at  Rowe’s Wharf, with its great dome and welcoming arch — an eerie reminder of the arch at Mumbai (Bombay) built to commemorate the visit by 1911 King George V and Queen Mary to India, except that Rowe’s Wharf consists of offices, palatial apartments and one of Boston’s fanciest hotels.

(Bombay, you should know, conscious of its growing international stature, has renamed itself for a local goddess, 400 years after the Portuguese explorer Francis Almeida sailed into its natural harbor and dubbed it Bom Bahia, or Good Bay.)

The Boston courthouse, in counterpoint to Rowe’s Wharf, proclaims the public’s business to be just as important as all that that private pomp. Justice is to be pursued in understated architectural splendor in a location every bit as grand. That does not mean it cost as much. The site was bought by the government for a song at the bottom of the 1989 recession, from a cash-strapped restaurateur. The building, designed by Henry Cobb and Ian Bader for the firm of Pei, Cobb, Freed and Partners, was cleanly and quickly built and has won several awards.

But what about the cost overruns on the Big Dig? Isn’t it true that the estimate of its cost went from $2.8 billion in 1983 to $6 billion in 1990 — to an estimated $15 billion today? The low-ball first figure, as authorized by the Reagan administration, included neither adjustments for inflation nor mitigation of ill effects.

When the government changed its bookkeeping under President George Bush, the bill was doubled overnight, to reflect the real costs. But the real escalation in the price tag for the Big Dig took place during the 1990s, when Republican Gov. William Weld took four years to redesign the river crossing. Experienced public managers fled the project.

In contrast, the Massachusetts Water Resources Authority set out about the same time to clean up Boston Harbor, under orders from a federal court. The estimated price tag for new sewers and a new sewage treatment plan in 1990 was about the same — $6 billion. Eight years later, the harbor project was completed by its Democratic Party administrators — on budget and on time.

The saga of Pittsburgh’s cleanup was always told, not inaccurately, as being a combination of “Democratic brains and Republican money.” The story has changed since then. Now it is the Republicans who have the brains .But the Democrats, more often than not, are the party of responsibility, at least with respect to domestic policy. And the essence of their identity crisis today is the immensely complicated search for another, similar formulation that rolls as easily off the tongue.

It was during the years that former Gov. Michael S. Dukakis held sway in Massachusetts that most of the pieces were put in place for Boston’s civic renaissance — civil servants appointed, funds sought, suits brought, policies pursued. The Big Dig is only the most expensive expression of a political culture that took very seriously the proper management of the public household.

By the time that the Democrats arrive in 2004, Boston’s airport, waterways, highways, bridges, tunnels, train stations, subways, parks, hospitals and public buildings will be sparkling. That’s not a bad story to tell the world about what the Massachusetts Dems have been doing during the period of their eclipse.