The Iron Throne
Aegon the Conqueror, the first of the Targaryen Kings, forged the Iron Throne after conquered six of the seven kingdoms of Westeros unifying them under his rule. Dover, the seventh kingdom, joined later after a marriage alliance.
It’s a signal of power and authority over the Seven Kingdoms because contains the swords of those Aegon defeated in battle, but not of those who had surrendered honorably. It’s uncomfortable to sit due to the blades and can cut the incumbent to remember to the heirs that no ruler should ever sit upon the throne carelessly as they must not rule carelessly.
The Iron Throne is located in the Great Hall of the Red Keep in King’s Landing, was the throne where The King of the Andals, the Rhoynar, and the First Men sat.