At 90 meters (295 feet) tall, "Big Air Package" occupies the entire internal expanse of the Gasometer Oberhausen - a former industrial gas tank turned events space and exhibition hall. It's also Christo's first project without his creative collaborator and wife Jeanne-Claude (1935-2009).

Workers securing the fabric dome appear Lilliputian; such is the monumental scale of Christo's design. "Big Air Package" is made from 20,000 square meters (215,000 square feet) of fabric and weighs in at 5.3 tons. Christo and Jeanne-Claude first had the idea for an air sculpture with their work "Air Package," produced for the documenta IV art exhibition in Kassel in 1968.

The sculpture was completed three weeks before the official unveiling on March 16. Christo said that he was "totally overwhelmed" by his own work. Photographer and project manager Wolfgang Volz has been working with Christo for 42 years. "It feels like being in a heavenly chamber," he told DW of his "Big Air Package" experience.

Christo and Jeanne-Claude were last in Oberhausen in 1999. Back then they created a sensation with "The Wall," a 26-meter-high wall made from 13,000 oil drums. "Art has to be useless," was the answer Christo gave a number of years ago when asked why his art is always so monumental in scale.

It took 23 years for Christo and Jeanne-Claude to get permission to cover Berlin's Reichstag in 1994. One year later, the work attracted flocks of tourists to the German capital and is now a celebrated part of the city's cultural history. Examples of such monumental works by Christo and Jeanne-Claude are on display in an accompanying exhibition in the Gasometer.

The art of Christo and Jeanne-Claude is always temporary. "The projects deal in large part with freedom," Christo explained. Artworks by the duo cannot be bought or owned. "The projects have a quality of fragility and tenderness, like our own lives or our own childhood. They cannot be substituted or repeated." "Wrapped Trees," pictured, was realized in Basel, Switzerland in 1998.