Rare historical items have been discovered in Washington at the site of the former Korean Legation to the U.S., where restoration work is under way. 

The 15 items include an invitation to the 1906 wedding of a daughter of then-U.S. President Theodore Roosevelt, business cards and Christmas and New Year's cards.

The Cultural Heritage Foundation and the Overseas Korean Cultural Heritage Foundation said the items show active diplomacy Korean envoys were engaged in during the 1891 to 1910 period.

The agencies said that the invitation to the White House wedding of Alice Roosevelt is of particular historical importance as it came after Japan deprived Korea of its diplomatic power in 1905 ahead of the formal annexation in 1910.

The restoration work on the former legation began in October 2015 and is set to open as a museum during the first half of next year.