Thousands of mansions in a remote corner of India once housed some of the nation’s wealthiest bankers and traders but a century later most of them lie abandoned, their desolate remains a mute testament to lost riches. The tycoons of Chettinad, near the country’s southern tip, made their fortunes trading precious gems and spices across sprawling business empires that stretched as far as Malaysia and Singapore during the era of British colonial rule. Much of their wealth was channelled into the construction of resplendent homes, embellished with stucco figurines, colourful glass windows and corn…