BERLIN -- ''And here, ladies and gentlemen,'' said the tour guide, ''just here along next to the Reichstag, you must imagine the Wall.'' A silence in the bus as everybody tried. Eight of the nine travelers in this American group had memories to draw on, but I, the ninth, had never laid eyes on divided Berlin. Now, a year after its broaching, the Wall in the area around the Brandenburg Gate is gone without a trace. Except for the emotion on the faces of my friends, I might as well have been straining to imagine the past at Verdun or Gallipoli.

History and memory are often invoked in the same breath, as twins or as extensions of one another -- but in fact they sit on opposite banks of a chasm that can be leaped only by a determined effort of the imagination. For first-time tourists now flooding Eastern Europe, whether with grandiose notions of business success or just wanting to understand, that chasm is going to pose more than trivial barriers. How can a newcomer imagine a newly liberated country's past, especially when with its horrors, it is basically unimaginable? On the other hand, if newcomers can't be made to imagine it, then how will this grand shock and upheaval of history be passed on to those who never saw it?

As Germany and Berlin have commemorated the one-year anniversary of the falling of the Wall, such questions are implicit in every museum show and lecture and concert. Occasionally they are explicit; more often, though, and understandably, the emphasis is still on the experience of those who lived through the upheaval and are living through it still. ''The Goddess of History follows you -- why?'' asks a garishly done-up mannequin in an advertisement on the Kurfurstendamm, the main shopping drag. ''Come find out at the Wall Museum.''

The struggle with history and memory is not exactly news to West Germans, of course. And the task here -- remembering what was gained in a peaceful revolution -- is relatively happy and simple work compared to the still-unfinished agonizing and arguing and self-justifying over the Nazis. Still, it's a challenge. ''I must have crossed at the checkpoint 50 times,'' said one of my bus colleagues, a scholar who'd lived on both sides, ''and I still sort of can't believe any of it happened.''

After all the news stories and TV coverage, I got my first actual look at the terrible No-Man's-Land in the sunny early morning of Oct. 3, unification day. Without the Wall it was a long, open, grassy expanse, busy with souvenir stands and Berliners walking their dogs, for all the world like the Mall in Washington. Could this place really be as haunted as it must be, I thought, could it really be the site of all those killings? And that raised knoll, it couldn't really, could it, be Hitler's bunker? The best way to hopscotch into memory is probably the copious literature the Wall and communism generated. But even literature is going to have a tough time with this one.

In Leipzig, the East German city where last fall's demonstrations really got rolling, the locals on a weekend morning crowd into an exhibition called simply "Fall 1989" in the St. Nikolai Church, an early haven for dissent. The pictures show mass demonstrations on a rainy Karl Marx Platz, the street lamps glinting off hundreds of thousands of umbrellas. More arresting still is a clipping from the state-controlled Leipziger People's Newspaper referring in its deadpan way to "large groups of people who disturb the public order and security, which was then restored." But the faces are the real show. These aren't people visiting a museum, they're people flipping through a favorite scrapbook.

Outside the museum, though, the distinction between history and immediate memory is harder to pinpoint. It might not be visible at all but for one small problem: the gap here is not just between Germans and curious tourists, but also between East and West Germans, for each of whom the other's immediate memories are as yet only history and hearsay. You notice it more in the election advertising for the Dec. 2 elections. Subtle differences in strategy show up even on issues where there seems to be basic agreement -- like, regrettably, the enthusiasm for taking away rights and privileges from "foreign" guest workers, such as Turks and Vietnamese, even though a lot of these people were actually born here.

In major intersections around Berlin the dominant conservative CDU has put up large placards with two dialogue-balloons: "I'm against voting rights for foreigners." "So am I. Only a CDU majority will put a stop to it." Winning issue or not, it seems an odd source of imagery to appeal to people who recently won back their own voting rights under such duress.

But it's not as odd and horrifying, or as unexpected, as the echo in a nasty little rhyming graffito scrawled on an East Berlin subway car, "Siehst du einen Turken laufen, muss' dir einen Messer kaufen," it says -- if you see a Turk walking, buy yourself a knife. Whatever West Germans may really feel about Turks -- and a lot of it isn't pleasant -- most of them have been taught in school, and painstakingly, not to rouse those particular echoes. The imaginative leap into the horrors of history may be hard work, but it has its eventual small payoffs. Some Easterners, it seems, still have it to learn. It dawns on the visitor, slowly, that there really was a Wall all those years. The writer, a member of the editorial page staff, is spending a year in Germany on a fellowship from the Alexander von Humboldt Foundation.