It may be his home and as big as two soccer fields, but chief executive Donald Tsang Yam-kuen always shows a more formal side in the corridors of Government House. 'Actually the living area for me and my wife is just a bedroom. When we leave our bedroom, we need to be properly dressed - not necessarily with ties, but we cannot leave our bedroom in our pyjamas and slippers,' the building's 26th resident told the makers of an RTHK documentary about the historic site. 'It's because once we leave [the private quarters], we see our colleagues. Some of them stay up late to work. It would be embarrassing for them to see me in pyjamas and slippers.' The documentary has been made for the 155th anniversary of the official residence in Upper Albert Road. Over the decades, the address has been the seat of power for colonial and wartime governors, has hosted legions of VIPs and evolved through several major renovations. Now a declared monument, the multifunctional neoclassical building serves as a home, an office as well as a ceremonial reception centre. It is a role that the chief executive is well aware of. 'A residence is different from a home - it has its own history. So I always have a feeling that I am only a passing visitor,' Tsang said. Designed by the colony's second surveyor general, Charles St George Cleverly, work on the house started in October 1851 with an estimated cost of GBP14,940. Until then, governors had lived in humble record offices or rented rooms. The project started under the third governor, George Bonham, but was not completed until 1855 when his successor, John Bowring, was in office. Antiquities and Monuments Office curator Ada Yau Lau Kwau-yau said problems with contractors and a shortage of building materials held up construction. Yau said the British government was not willing to put much money into the colony at the time, so the house was built on a much smaller scale than similar buildings in India. Bowring even had to buy his own furniture, which he sold when he left office. 'He sold all the furniture through auction ... because he earned very little. It was really embarrassing for his successor,' she said. The building has had its fair share of problems. Yau said that although asphalt was used to prevent termites, the roof had to be replaced 20 years after it was built because of infestations. That work was followed by a major expansion in 1890 under William Des Voeux, who added a two-storey annex on the eastern side to allow more space for social functions. The structure was severely damaged several decades later when a tunnel was dug underneath the house in preparation for the second world war, but repairs had to wait until the Japanese military occupation. In 1942 governor Rensuke Isogai ordered engineer Seichi Fujimura to build a central tower to underscore Japanese sovereignty and streamline pillars and pediments. Isogai ordered the alterations because he was not satisfied with the house, according to documentary producer Ricky Lee Tze-leung. 'He wondered how the Hong Kong governors could bear living in such poor conditions,' Lee said. The Japanese did not make major changes to the building's layout. When Mark Aitchison Young, the governor who surrendered to the Japanese, returned to Government House in 1945 he removed all of the interior decorative elements installed by the Japanese. Since then, almost every governor has made some alterations to suit their own style and needs. These days Government House is not the mysterious bastion of power that it once was, with the building open two days each year for public viewing. The documentary, The Government House - 155th Anniversary, will air tonight at 7pm on TVB Jade.