Film-maker S Shankar, who is currently directing South Indian superstar Rajnikanth and the Bachchan bahu Aishwarya Rai Bachchan in his sci-fi big budget film Endhiran, has created a huge glass chamber-like structure to shoot a romantic song sequence.

Reliable industry sources say the structure which took almost over two weeks to construct will only be used to film some shots that will be a part of a particular romantic duet.

Our source says, "Aishwarya and Rajnikanth will be filmed romancing each other inside this glass chamber for a romantic duet. It is a completely closed structure and so shooting cannot take place continuously. They will do few shots inside this with Rajni and Ash. The entire song is not being filmed inside this structure. It is most probably being used to enhance the visual appeal of the song sequence."

The film has a mammoth budget of Rs 140 crore, perhaps making it the most expensive film to be made in India to date. Rajnikanth plays a double role of a scientist as well as a robot.