You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "when did the berlin wall start being built?" whose answer is ), starting on.
Each document should contain about 30 words, and these documents should contain useful information.

Query: when did the berlin wall start being built
Useful Output:

Doc 1: The Berlin Wall was built in 1961, at a time when Europe was divided in two. The wall itself divided the German capital city of Berlin for almost 30 years.
Doc 2: On 13 August 1961 the East German government decided that the border needed to be properly closed and the Berlin Wall was put up. East German
Doc 3: One central memorial site is the Berlin Wall Memorial. It was built in 1998 on what used to be the border strip at Bernauer Strasse. The
Doc 4: Constructed by the German Democratic Republic (GDR, East Germany) starting on August 13, 1961, the Wall completely cut off West Berlin from surrounding East
Doc 5: On 13th August 1961, citizens of Berlin woke up distressed and confused to a wired barrier circulating around West Berlin, preventing East