Principal photography began on March 14, 2016, in Vancouver, British Columbia. Previously it was revealed at San Diego Comic-Con International that filming would begin in February 2016.\n\nWhen did they start filming the death cure?
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The relevant information to answer the above question is: Principal photography began on March 14, 2016, in Vancouver, British Columbia.
So, the answer is March 14 , 2016.
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