How long did it actually take to decipher the Rosetta Stone?

The answer

The Rosetta Stone, discovered by Napoleon's soldiers in 1799 near Rashid (Rosetta), Egypt, bears the same decree in three scripts: hieroglyphic, Demotic, and ancient Greek. Decipherment took 23 years and centered on a fierce rivalry between England's Thomas Young and France's Jean-François Champollion. Young made initial breakthroughs in 1814, identifying that cartouches contained royal names and that hieroglyphics had phonetic elements. But it was Champollion who achieved the full breakthrough in September 1822, demonstrating that hieroglyphics were a complete writing system combining logographic and phonetic elements. The stone, dating to 196 BCE under Ptolemy V, has resided in the British Museum since 1802, where Egypt continues to request its return.