1. Pan of creator of Berlin wall cycle trail, Michael Cramer and his friend Guenter Warnecke riding bikes at Potsdamer Platz

2. Tilt down of watch tower

3. Low angle of Cramer and Warnecke climbing up inside the watch tower

4. Wide of building seen from window of watch tower

5. Cramer and Warnecke riding their bikes

6. Tilt down from wall to Cramer and Warnecke visiting Topography of Terror memorial

7. Cramer and Warnecke visiting memorial

8. Close of wall at Topography of Terror memorial

9. SOUNDBITE: (German) Michael Cramer, initiator of the wall bike trail:

"Over there is one of the ministry buildings. It was the former air traffic ministry of the Nazis. There on June 15th 1961, former GDR (German Democratic Republic) leader Walter Ulbricht said, ''Nobody has the intention to built a wall''. But here is the wall."

10. Cramer and Warnecke riding their bikes along wall trail

11. SOUNDBITE: (German) Michael Cramer, initiator of the wall bike trail:

"Peter Fechter was one of the first refugees to be killed. It was especially tragic because his friend made it into West Berlin. Fechter was stuck in barbed wire and was shot. For four hours nobody cared. The Allied forces and Berlin police did not want to, and could not help him and the other side (East) did not care. He finally bled to death."

12. Cramer and Warnecke riding their bikes along the former wall

13. SOUNDBITE: (German) Guenter Warnecke, bike and history enthusiast:

"13th of August 1961 was a Sunday. I was was at a sports ground and someone had a radio there where we heard about the construction of the wall. As a result, I noticed a couple of days later that my fellow students from Teltow, Babelsberg and Potsdam (in the former east) disappeared."

14. Cramer and Warnecke riding along the former patrol road

15. Cramer passing by "East side gallery"

16. Close of bicycle

17. Pan of Cramer and Warnecke arriving at "East Side gallery"

18. Set up of historian at Bernauer Strasse, Guenter Schlusche

19. SOUNDBITE: (German) Guenter Schlusche, Historian:

"The leaders of the GDR were under pressure to act because more and more people were leaving the country, in the time, the months and years, before the wall was built. The GDR leaders didn''t or did not want to see the reason for it. That''s why they decided to built the wall."

20. Wide memorial for victims of the Berlin wall at Bernauer Strasse

21. Photographs of people who died at the wall

22. SOUNDBITE (German) Michael Cramer, initiator of the wall bike trail:

"Only someone who knows the past can face the future. We all want to be able to deal with our future, that''s why we have to know our past. The bicycle is fast enough to see a lot and slow enough to take it all in."

23. Cramer and Warnecke on their bikes

24. Pan of East Side Gallery

Fifty years after East German authorities constructed a wall through the heart of Berlin, only at a few pieces remain of the once formidable barrier that divided the city in two.

Although the former wall is one of Berlin''s biggest tourist draws, the attractions relevant to the structure are far-flung and difficult to find.

It is not only foreign visitors who struggle to figure out where the barrier once stood.

A young generation of Berliners has hardly any reminders of their city''s - and nation''s - once defining barrier.

Michael Cramer, a member of the left-leaning Greens party decided it was important to keep parts of the wall visible as a reminder of the city''s turbulent history.

After campaigning for 10 years, he and his party have established the Berlin Wall Trail, a bicycle path to mark the former strip where the wall once stood.

The Berlin Wall Trail traces the course of the former GDR (German Democratic Republic) border fortifications that encircled West Berlin.

For nearly three decades, the former western enclave in the heart of communist Germany was surrounded by the nearly 160-kilometre (99-mile) barrier.

The bike trail starts in the centre of Berlin, at Potsdamer Platz, formerly a no-mans-land between east and west.

The first stop is only a few metres away - one of five former East German watch towers that still stand today.

More then 300 watch towers were built along the former inner-German border and used to prevent people from escaping the former GDR into the west.

From Potsdamer Platz, the trail leads to another place soaked in the history of the former GDR, and the Nazis before them.

At the place where today the Topography of Terror memorial site now stands, the Nazis tortured people during interrogations at the former Gestapo headquarters.

Right behind it is the house of the ministries where history was written several times.

"It was the former air traffic ministry of the Nazis," says Cramer. "There on June 15th 1961, former GDR leader Walter Ulbricht said ''Nobody has the intension to built a wall''. But here is the wall."

More than 230 people died at the Berlin Wall.

The first was Guenter Liftin on August 24th 1961 and the last Chris Gueffroy on February 6th 1989.

Recently erected columns along the bike path with the names of the victims honour those who died.

"Peter Fechter was one of the first refugees to be killed," Cramer says. "It was especially tragic because his friend made it into West Berlin. Fechter was stuck in barbed wire and was shot. For four hours nobody cared. The Allied forces and Berlin police did not want to and could not help him, and the other side (East) did not care. He finally bled to death."

City authorities have laid down an eight-kilometre (five-mile) long, double row of cobblestones through the heart of the city to mark the course of the wall.

The entire wall ran some 40 kilometres (25 miles) through the city.

Since 2001, Guenter Warnecke, a 72-year-old Berliner has regularly ridden along the wall trail.

The former engineer was a student in 1961 and remembers the historic day when suddenly his former classmates who lived in the east were no longer around.

"I was was at a sports ground and someone had a radio there where we heard about the construction of the wall," Warnecke recalls. "As a result, I noticed a couple of days later that my fellow students from Teltow, Babelsberg and Potsdam (in the former east) disappeared."

The bike trail runs along the former patrol road used by customs officers in West Berlin, or along the control road used by GDR border troops for their own patrols.

Sections of historic interest, with traces or remains of the old wall, alternate with stretches of natural beauty.

The last section of the inner wall has become famous all over the world as the "East Side Gallery."

Its pictures, painted by various artists in 1990, were carefully restored to their original brightness in 2009.

In recent years, the efforts to preserve the Berlin Wall, including the bike trail, have made it one of the city''s top tourist attractions.

Germans and foreigners alike flock to see pieces of the former barrier to contemplate the lessons it can bring to future generations.

"Only someone who knows the past can face the future. We all want to be able to deal with our future, that''s why we have to know our past," says Cramer. "The bicycle is fast enough to see a lot and slow enough to take it all in."