Baltimore is celebrating its row houses, as well it should.

Far more than its Washington monument (which predates our own) or its renovated Grant-era city hall or the skyscrapers of the new downtown or the dramatic new aquarium building on a pier in the rejuvenated harbor, the row house is the symbol of this working-class city.

Whether one is driving around in the Baltimore neighborhoods or merely passing through in a train, streets lined with low-lying houses, each with its set of steps leading directly to the sidewalk, make up the major visual impression one takes away from the city.

So it makes great sense that the Peale Museum, after a two-year, $1.3-million renovation, re-opened with an exhibition devoted to the history of the row house in Baltimore.

The exhibition is timely in more ways than one, and it could with profit be imitated in Washington where, despite differences in style, size, materials and demographics, the row house also is the dominant type of dwelling.

Because I live in a row house, I must admit to some prejudice in its favor. In terms of urban design it is an imminently flexible type of building, capable of an almost endless variety of stylistic expression. This makes for visual interest; it also makes for lively streets. In terms of population density, it is an excellent compromise. It is economical, too, if anything is now.

Most importantly, perhaps, the row house is there. As William H. Whyte has pointed out, "One of the most impressive things about our medium-sized 'aging' cities is the wonderful stock of close-in housing," but he may as well have included larger cities such as Washington and Baltimore, where thousands of row houses, dilapidated or not, constitute an important resource waiting for use.

Whether they will be used to help allay the housing problems of the poor and the elderly is another question, especially in these days of federal cutbacks and trickle-down economics. At the very least, however, government policies favoring the destruction of these homes in the name of large-scale urban renewal projects have been thoroughly discredited.

The thorny issue of "gentrification" is much on the mind these days -- that is, private-sector renewal of this housing stock accomplished mostly by younger, affluent white people who often displace poorer residents. This is a significant issue, but the gentrification movement hardly is the root cause of the intransigent housing problems of the poor, and it does give something important back to the city. Whyte goes so far as to call it "absolutely vital to cities."

In any case, this movement, like the exhibition at the Peale Museum, is yet another sign that the row house is coming back into its own. For a visitor from another city, much of the exhibit's fascination is the mental comparison: So much of the reason Baltimore is Baltimore, and definitely not Washington, is due to the near uniformity and near ubiquity of its row houses.

One of the prominent differences between the two places is the relationship of the houses to the street. In Washington, the typical row is set back from the sidewalk and provided with a modest front yard around its porch or protruding bays; in Baltimore even the earliest rows, constructed during the first half of the 19th century when the city was well on its way to becoming a booming port, were plopped directly on the sidewalk. Porches and bays were almost unheard of, and the famous Baltimore steps were simple affairs, usually without railings.

In the 1850s, brick buildings with Italianate cornices and door moldings replaced the simple, quasi-federal houses, and toward the end of the century eclectic Victorian ornamentation made its appearance. Despite these changes in style the basic unit remained much the same, and the pattern of directly abutting the sidewalks remained the norm. Only in this century did the pattern change significantly, when suburban-like "Daylight" houses with porches and modest yards were built in profusion in then-outlying areas of the city.

Although Baltimore certainly does not lack elegant rows constructed for its wealthier citizens -- the brownstone homes on Mount Vernon Place near the Washington monument are one significant example -- the exhibition with reason focuses almost exclusively upon the modest dwellings constructed for the people who built the city and work in its factories. The buildings were small, inexpensive to build and, because a system of "ground rents" assured builders of profits, relatively easy to buy.

These are the homes that establish the visual and social identity of the city more than any others. Baltimore is a city of ethnic neighborhoods. Whether by design or by the accident of economics, the prevailing housing type profoundly reinforces this reality by requiring so much of the life of its residents to take place on the stoops or in the streets. The design led to overcrowding (and still does) but it also helped to foster a sense of community among residents of a given block.

It also helps to explain a form of folk art peculiar to the Baltimore row house: the screened window or door painted with a bucolic scene that one still can see on many a Baltimore street. Esthetically, the painted screen serves to decorate a house and differentiate it from its neighbors. Functionally, it provides peek-a-boo privacy. Residents can sit inside, more or less hidden from view, but still able to see the comings and goings on the sidewalk.

The exhibition, designed by the Washington firm of David Root and Patricia Chester, helps to bring this and other facets of the row house to life. In addition to slides and cut-away views of the major types, it presents examples of typical moldings, roofs, painted screens, stained glass windows and so on, along with a few authentically furnished period rooms.

In Washington the story is not quite so simple, the styles nowhere near so uniform. Still, as this show proves, we can learn a great deal about the history and character of a city by looking carefully at its main housing type. It would be a worthwhile study for somebody to make.

The show is on view indefinitely. The Peale Museum, named after Rembrandt Peale, who started a museum there in 1814, is located at 225 Holliday St., near City Hall. It is open from 10 a.m. to 5 p.m. Tuesdays through Saturdays and from noon to 5 p.m. Sundays.