It’s the week of D-Day. June 6. This city remembers. It doesn’t forget. Question: Is that remorse or guilt?

East Berlin, West Berlin. Kristallnacht — Nov. 9, 1938 — houses of worship set afire. That’s when it all began. The city’s a lifetime memorial of the dead.

There’s medieval history. Ancient history. American history. Berlin is a living history of what contemporary civilization endured. Bombed out, destroyed, razed to the ground. It’s education in Hatred 101.

The older generation won’t talk about it. The next generation won’t ask about it. The young generation wants to know about it. The Wall, dividing the city 28 years, was torn down in ’89. What hasn’t been torn down are the memories.

You can see Checkpoint Charlie, the hand-over spot in what was then the American sector. You can see embedded in the street, cement or cobblestones, small burnished square brass plaques, paid for by the government, marking where human beings once lived. Each bears their name, birthplace, residence, and the German word “ermordet” (for “murdered”) in Auschwitz with the accompanying date.

I’m traveling with Barbara Walters and my friend Geoffrey Weill, who specializes in international travel. One plaque memorializes his great uncle.

Within sight of Berlin’s pitted but indestructible 1788 landmark, the Brandenburg Gate, is its gloriously reconstructed postwar home to visiting heads of state, the Hotel Adlon. Having housed Garbo, Caruso, Chaplin, Einstein, Roosevelts, Rockefellers, czars, kings and the Kaiser, it’s forever immortalized with Michael Jackson dangling his baby from the terrace. My windows face the American Embassy on Pariser Platz. Preventing car bombs, its entrance is ringed with metal stanchions.

Germany’s capital yesterday was gray. Its tomorrow is rosy. Frederick the Great’s Köpenick district, now a tech center. Tegel Airport, dinky, thrown up in three months for the ’48 Berlin Airlift, replaced. Music and fashion businesses along the banks of river Spree. We’re talking museum country — the Old museum, New museum, National museum, Pergamon museum, Terror museum, Bode museum, Holocaust Memorial, Jewish museum designed asymmetrically like a broken Star of David by Daniel Libeskind.

Clothes? Its Greenwich Village is Hackesche Höfe. A cousin to Fifth Avenue is Kurfürstendamm. There’s Frederick II of Prussia’s reopened 1742 opera house. If you carry your passport, lunch at Kaefer atop the Deutscher Bundestag — architect Sir Norman Foster — is accessible to the public. Stroll Unter den Linden. View Kaiser-Wilhelm-Gedachtniskirche. Ruins of this 1895 church remain as a forever reminder of World War II. See Schloss Charlottenburg. In 1699, it’s where Queen Sophie Charlotte called home. Order Wiener schnitzel at Borchardt, which Ron Lauder calls the town’s best restaurant.

See the old and the new: Gestapo headquarters, the bunker where Hitler killed himself. The venerable synagogue, protected by the polizei, in what was the Jewish section. The “Abandoned Room” park sculpture of an empty table with empty chairs symbolizing where “they” lived. Gasp at Frank Gehry’s hyper super ultra modern DZ Bank. Look where they say Katarina Witt was born. Shop at Armani. Sip at Starbucks.

Berliners say, “We have a big heart — also a big mouth.” Dine at Pauly Saal, formerly a school named for bigmouth Bertolt Brecht, who, with Kurt Weill, delivered “Threepenny Opera” and brought us Lotte Lenya. Or have a lakeside country lunch outdoors at — if you can pronounce it — Die Fischerhütte am Schlachtensee. The boiled beef and horseradish is great.

And 25 minutes away? The castle of Kaiser Wilhelm. Not the de Blasio one schlepping into Gracie. The gigantic marble, crystal, gilt, art-laden, hand-carved rococo Prussian one who actually owned the place. And around the corner? The stewpot of survival. Schloss Cecilienhof’s large round conference table dominated by three equal red velvet gilt thrones. The Potsdam Conference. July/August 1945, there sat Truman, Churchill and Stalin, carving up Germany.

When I first visited divided Berlin, it was drab. Grim. No shops. No smiles. Now Berlin is a tourist trap. Huge buses with travelers. Affordable housing. Low prices. Clubs, discos, late-night dancing. No Bavarian outfits. Not lots of sauerbraten and kartoffel. It’s McDonald’s. Guys in tees and jeans. Chicks with long, flat hair and tight, short skirts.

Today’s world has homogenized. We drive German cars. Buy their beer. Eat their sausages. They love American style. American music. American TV. So . . . why can’t we all get along?