I want to know the answer to the following question:
When were Napoleon I's remains interred in his mausoleum?
All the background I'm provided with is that "They visited the Exposition Universelle (a successor to Albert's 1851 brainchild the Great Exhibition) and Napoleon I's tomb at Les Invalides (to which his remains had only been returned in 1840), and were guests of honour at a 1,200-guest ball at the Palace of Versailles.". Is that enough to answer the question?
Answer: yes