Former US President Barack Obama has said America was founded on the principle that “there will be no kings” at the opening of his presidential centre in Chicago.

The star-studded dedication was attended by three former presidents, with music from performers including Jennifer Hudson, Bruce Springsteen and Stevie Wonder.

Obama used his speech to praise democracy and urge unity, saying the American people “want to find a way to turn towards each other again, not further away”.

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