Reading maps can be a good way to brush up on history - but you can also make money from them as well.
Christopher Bailey, 45, an investment banker-turned-map collector, and gallery owner Jonathan Wattis, 55, say there is a big demand in Hong Kong for old maps. 'I can never find enough maps of Hong Kong. Early maps, or unusual maps,' says Wattis of Wattis Fine Art gallery.
Bailey says that if he could get another 30 maps of the city he could sell 60 to 80 a year, rather than the 30 to 50 that pass through his gallery, Picture This.
Four years ago, Wattis sold an 1843 Hong Kong map which is now valued at more than HK$300,000.
Bailey recently sold an 1845 sea chart for HK$140,000 and three years ago sold a 1760 French sea chart, with some details of Hong Kong, for HK$300,000.
A lot of the early chart makers made many mistakes, like showing the Korean Peninsula as an island. And they also stole ideas from each other. On one map it says: 'The Philippine Islands took their name from Phillip II, king of Spain.' This phrase is repeated exactly on a 1730 map and again on a 1747 map.