Six years after enveloping the building of the Reichstag, Christo and his wife Jean-Claude returned to Berlin again. In the capital of Germany they open an exhibition with more than 400 early works of theirs, AP announced. Among the different exponents there are enveloped trees, bicycles and chamber-pots. The exposition includes even a model of a pilot balloon, dating from the middle of the 60ies, when the couple enveloped air. `Never we have had such a big exhibition`, Jean-Claude said about the exposition, covering the period 1958 - 1969. The exhibition is in the `Martin-Grupious Building` and will be accessible for visitors till the end of the year. At the same time a second exposition in Berlin will show drawings and photos of future projects by Christo and Jean- Claude. One of them plans an area of a several miles of the river of Arkansas in Colorado to be covered with a nylon tissue. And the second is about the building of 11,000 steel framed doors in the Central Park in New York.