TODAY Military moves: Last ceremonial guard mount, Prince of Wales Barracks, Central, 9.15 am, free. Flag day: Taxis and public light buses carry the SAR flag, Sha Tin racecourse, 9 am-1 pm, 2667 7091. They're off: 1997 Baby Crawling Contest, Hong Kong Exhibition Centre, 10 am-7 pm, 2811 4522. Musical evening: The Last Night of the Proms, Hong Kong Academy for Performing Arts, Wan Chai, 8 pm, $295-$695, 2805 2804. NANJING Fireworks will be set off in six districts at 8 pm on Monday. It is hoped people living in every corner of the city, where the Treaty of Nanjing ceding Hong Kong Island was signed 155 years ago, will come to watch the displays. A giant clock situated in the heart of Jinghai city, site of the treaty negotiations, will strike 155 times at midnight to mark the end of the so-called 'unequal treaty'. The 1.842-metre diameter clock symbolises the year of the treaty while its total height of 1.997 metres marks the change of sovereignty. Hong Kong passengers boarding the first flight to Nanjing's new Lukuo Airport on Tuesday will be greeted with flowers, dances and singing.