Hello.
Louis XVI was beheaed by guillotine in the Place de la Revolution in Paris.
He was put to death on January 21, 1793
He was executed because of treason; he had been accused of betraying the French nation to the Austrians. Now, in fairness, Louis XVI had pretty clearly tried to flee Paris in order to organize a counter-revolution. This soured opinions on the King, and, in 1792, when the armies of the Coalition looked on the verge of taking Paris, he was accused of being part of an enemy plot, deposed, and executed months later.
Have a nice day