Burce Greenberg's voice is low, almost a whisper. It seems to get that way whenever he starts reminiscing about old trains.

"What I do," he says, "is go down to my basement where I have the train tracks all laid out. I turn off the lights, start the train rolling. Slowly at first, but then it picks up steam. Suddenly it rounds the bend and heads down a straight length of track.

"When the headlight flashes and the whistle blows -- whoo whoo! -- man, that's it. It takes you back. You feel like you're watching one of those old-time locomotives roar down the line."

Several years ago, it dawned on Greenberg, a book publisher from Ellicott City, that he probably wasn't alone in his infatuation with the iron horse of yesteryear.

As he puts it, "There are a lot of people out there who love trains."

So in 1976 Greenberg held the first of his Great Train Shows, where train buffs swap, buy, sell or gawk at everything from old American Flyer sets to authentic Pennsylvania Railroad conductors' uniforms to parts from early-20th-century trains.

Greenberg's festival of trainmania has grown so successful that it now takes place three times a year. The next one is slated for July 13 at the Towson Center in Towson, Maryland.

Two hundred exhibitors will set up booths and, if past crowds are any indication, more than 5,000 people might attend that Sunday gathering.

"A lot of those 5,000 will be adults," Greenberg points out. "Male adults," he adds with a self-conscious laugh.

"These are people who attained a passion for model trains when they were very young. Then, as adolescents, they might have put them aside in favor of other things. But later, when they started having kids of their own, they dug the old Lionels out of the attic and rekindled the flame."

Greenberg has a one-word explanation for all this locomotive madness: "Nostalgia. Many people feel a certain longing for the old days, when we had those steam engines that banged and hissed and clanged and made all kinds of wonderful sounds and movements. It's all so different from what we have today in trains.

"That's why the Great Train Show. It's a chance to go back."

Nostalgia. It's the impetus behind so many of the festivals going on this summer and fall in the area.

There's the Old-Fashioned Apple Harvest Festival, an Old-Fashioned Fourth of July, the Old Threshermen's Reunion (held, no doubt, to thrash over old threshing). There's even a three-day celebration called, rather simply, the Notalgiafest.

However, for those sentimental souls who fail to find total satisfaction with a sojourn into the recent past, there are festivals that go farther down memory lane, recreating historical events or epochs: the Jonathan Hager Frontier Crafts Day, Yorktown Day, the Oxon Hill Jousting Tournament and, perhaps the granddaddy of them all, the Renaissance Festival in Columbia, which will probably draw about 50,000 people this year.

Held for five weekends in September and October, the Renaissance Festival serves up such unique forms of entertainment as madrigal-singing, mime, swordplay, equestrian events, a mock battle between two contingents of mail-clad would-be Galahads, Renaissance dancing, actors reciting Shakespeare and a game or two of "human chess."

"In human chess," explains festival director Marlene Weinberg, "we get people from the crowd to hold large chess pieces and stand on a stage that has a giant chessboard painted on it. The match will be between two people portraying a king and queen. This is just as they used to do it in olden times."

In olden times, they also used to lop off the head of the poor slob whose piece happened to taken. Will this hardy tradition be followed at the Renaissance Fest?

"Well, we'll make a small scene as if were actually going to do it," Weinberg says, "but we won't really be beheading anyone, rest assured."

Of course, not every festival is strictly a sentimental journey.

A good number of these summertime and autumn assemblages revolve around that ever-popular twosome, food and drink. While the former provides the theme for the Maryland Seafood Festival, the McClure Bean Soup Festival, the Oyster Festival and the Peanut Festival, the latter supplies the justification for the Middleburg Wine Festival and Vineyard Tour and the Gemuetlichkeit Bierfest.

In addition to a grape-stomping contest (with the top juice-producer copping a silver cup), the Middleburg Wine Fest offers a "wine-growing seminar," in which chemical scientists and wine-industry officials discuss the ins and outs of concocting the beloved Dionysian delight.

Another type of celebration that has become increasingly popular in recent years is the ethnic festival.

Along with Baltimore's weekly salutes to everyone from the Estonians to the Hispanics, this year's list of ethnic fests includes Richmond's International Festival '80, the Polish Festival in Doylestown, Pennsylvania, and new entry, the Maryland Irish Folk Festival in Mount Airy, which promises to become one of the best and biggest festivals around, ethnic or otherwise.

Two years in the planning, the Irish Folk Fest has already sold 10,000 advance tickets, with some sales coming at Ticketron offices in Chicago and Boston.

The entertainment line-up boasts more than 200 Irish folk musicians and dancers, many making the trip from the Emerald Isle for the first time. Even the U.S. ambassador to Ireland, William Shannon, is expected to drop in on the festivities, which get under way next Saturday, July 12.