The linked BBC article in the HN post has the list for top 10 richest man in history with Mansa Musa at the very top but Shah Jahan the Mughal Emperor who's the owner of Taj Mahal is not even in the list [1].
The 10 richest men of all time:
1) Mansa Musa (1280-1337, king of the Mali empire) wealth indescribable
2) Augustus Caesar (63 BC-14 AD, Roman emperor) $4.6tn (£3.5tn)
3) Zhao Xu (1048-1085, emperor Shenzong of Song in China) wealth incalculable
4) Akbar I (1542-1605, emperor of India's Mughal dynasty) wealth incalculable
5) Andrew Carnegie (1835-1919, Scottish-American industrialist) $372bn
6) John D Rockefeller (1839-1937) American business magnate) $341bn
7) Nikolai Alexandrovich Romanov (1868-1918, Tsar of Russia) $300bn
8) Mir Osman Ali Khan (1886-1967, Indian royal) $230bn
9) William The Conqueror (1028-1087) $229.5bn
10) Muammar Gaddafi (1942-2011, long-time ruler of Libya) $200bn
[1] Is Mansa Musa the richest man who ever lived?