From the World Heritage inscription:
Jongmyo is the oldest and most authentic of the Confucian royal shrines to have been preserved. Dedicated to the forefathers of the Choson dynasty (1392–1910), the shrine has existed in its present form since the 16th century and houses tablets bearing the teachings of members of the former royal family. Ritual ceremonies linking music, song and dance still take place there, perpetuating a tradition that goes back to the 14th century.
The Jongmyo Shrine grounds is literally across the street from the Changdeok Palace compound. Like the Changdeok Palace, it suffers from a lack of fixtures and artifacts. Unlike the Changdeok Palace, you can enter the grounds with a ticket and stroll around the facilities to your heart’s content.