The only part of the Berlin Wall that now remains intact lies to the east of the city center, along the River Spree. It is also known as East Side Gallery for the many murals painted on the wall. There are some other places where parts of the wall remain standing. It is a fascinating reminder of the horrors of German history.

mmcholm-berlin_wall-04 (Source: Mike McHolm) 

A visitor says:

Portions of the original wall still stand and can be viewed along the highway. It has been painted with a variety of scenes and motifs. Much of it appeared to resemble graffiti instead of memories of an historical period. A few scenes were noteworthy but since Berlin considers that part of the existing wall to be a national memorial/monument, I would have expected something more impressive and less amateur.

 (Source: Berlin Wall - Berlin - Reviews of Berlin Wall - TripAdvisor) 

Address: Niederkirchnerstrasse, 10117 Berlin

Admission: Free

Timings: Always accessible

The Underground tours are organized by the Berlin Underworlds Association. This bizarre and spectacular walking tour will lead you into the weird interiors of a blasted air raid shelter from World War II. You will be able to explore two of the original 7 floors of Berlin's biggest bunker complex. Also lookout for a former ammunition elevator via a solid and safe steel construction.

Bunker Humboldthain (Source: Robert Agthe) 

A review:

Up to 50,000 people stayed in the lower levels of each of the big flak towers and the upper levels were reserved to military action. Be prepared to look into the abyss of a former ammunition elevator and thanks to a solid and safe steel construction, no one needs to suffer from altitude sickness! Now, the Flak Towers has been transformed from a shelter for human beings into a habitation for some of the most mysterious creatures of the night, bats.

 (Source: Berlin Flak Towers Underground Walking Tour) 

Address:Brunnenstrasse 105, 13355 Berlin

Phone:49-30-4991-0517

Tours:

Tour 1 - Dark Worlds
Tour 2 - From Flak Towers to Mountains of Debris
Tour 3 - Subways, Bunkers, Cold War
Tour B - The Bunker Tour
Tour D - Along the Tracks of D-Line
Tour M - Breaching the Berlin Wall

Address - Ticket Office:

Southern exit of the U8 station Gesundbrunnen, Brunnenstrasse 105.

Tour 1-3: 90 min - USD 14.27
Tour M: 120 min -  USD 18.55 

Tickets can purchased only on tour day and cannot be reserved in advance.

Departure Point: Tour commences from the Underground Station 'Gesundbrunnen'. The meeting point is easy to locate and your guide will be waiting for you. Departure Time:16:00pm

The Badeschiff (bathing ship) is one of Berlin's most unusual swimming pools. It is part art project and part contemporary solution to living in a polluted urban center. Originally  it  was conceived by local artist Susanne Lorenz and this anchored ship located on the Danube Canal has been converted into a club that is packed with interesting slideshows projected on the walls.

Badeschiff (Source: H. Füller) 

Here is a review:

Originally conceived by local artist Susanne Lorenz and made out of an old river cargo container, the Badeschiff floats atop Berlin's long-neglected and unswimmable River Spree. In the summer, the pool is completely uncovered, creating a mini-oasis of clean, cool water that puts swimmers almost eye-level with the Spree. DJs spin tunes as people frequent the open-air bar and hang out on the wooden boardwalks.

 (Source: Expatica Germany) 

Address: Eichenstrasse 4, Berlin

Phone:0157 - 876 259 19

Admission: USD 4

Timings: In the summer of 1 May: daily 8:00 - 0:00

Futuro House is one of the best offbeat attractions in Berlin. The brainchild of Finnish architect Matti Suuronen, the Futuro house was designed and constructed in1968. It is a prefabricated, mass-produced flying saucer like living complex for the future, which could even be delivered right to your home via helicopter.

 (Source: R. Steven Rainwater) 

A review:

It was built out of fiberglass-reinforced polyester plastic and was light enough to be lifted to remote sites by helicopter, where the steel legs could adjust to any terrain.

 (Source: Futuro: The UFO House Thats Out of This World) 

Address: Blockdammweg & Köpenicker Chaussee, near the former radio station of the GDR

The Kurfurstendammand and Tauentzienstrasse is a major shopping district in Berlin, which offers everything from upscale fashion addresses for some chic shopping to local stores where you can bargain to get a good deal. If you'd like to spend a day looking over fantastic things to take back home, Kurfurstendamm and Tauentzienstrasse will be your best bet.

Kurfurstendamm (Source: Kurfurstendamm) 

A review:

Kurfurstendamm in the exclusive Charlottenburg is propably Berlin's number one shopping street. It is a three kilometer long boulevard with a blend of shops and restaurants and a real shopper's paradise. In one end you will find the mainstream part with shops like H&M, Zara and Mango whereas the other end offers the more exclusive shopes like Gucci, Yves Saint Laurent and Chanel. If you are looking for something more unique go into one of the many side streets like Uhlandstrasse or Fasanenstrasse where you will find some really beautiful small boutiques of all kinds.

(Source: Berlin Property) 

Location: Charlottenburg-Wilmersdorf district

Strasse des 17 Juni is probably Berlin's best-known and classiest outdoor market. There are a variety of stalls here, selling everything from fancy artifacts, hand-crafted items to funky clothes, jewelry and records. This place is very popular with tourists and surely worth a visit.

 (Source: Flohmarkt an der Straße des 17. Juni) 

A review:

The weekend flea market on Strasse des 17. Juni is Berlin's largest and probably best-known market. Divided into two sections, one half specializes more in art, handicrafts and antiques, while the section nearer the Tiergarten Station is more your normal flea market, although with a higher class of junk than most. The market is organised in two long rows of stalls with limited space inbetween stalls, so it can get quite crowded: go early if possible.

 (Source: » Straße des 17. Juni (Flea market) - Berlin Guide in English) 

Location: Strasse des 17 Juni (just outside the Tiergarten) Berlin

Timings: 11am - 7pm