London, Sept. 25 (Jiji Press)--Japan's Mitsubishi Estate Co. held a groundbreaking ceremony on Thursday for a large office complex to be built along the River Thames in London. The complex, named 72 Upper Ground, is scheduled to be completed in 2029 at a total cost of about 160 billion yen, making it the company's largest-ever development project in Europe. With a total floor space of abo...