Tomorrow will be a bittersweet day at the National Zoo and Zoo Atlanta, as fans must say goodbye to Giant Pandas Tai Shan and Mei Lan respectively. Four year old Giant Pandas Tai Shan and Mei Lan have captivated crowds since their successful births, the first for both institutions. 

The pandas will be returned to China in accordance with the Zoos' original agreements. In fact, Tai Shan was supposed to return home two years ago but the Chinese government extended his stay for another two years.

(Below) Tai Shan back in 2005 at 11-weeks-old. This was during the cub's 7th check up, all of which he "handled very well," according to zoo veteranarians.

Photo: Smithsonian Zoo

Photo: Smithsonian Zoo

(Below) Snow falls on Tai Shan during his farewell celebration. The snow and frigid temperatures failed to deter Tan Shan's diehard fans from coming to say goodbye.

Photo: Jon McRay/FONZ Photo Club

(Below) Mei Lan snuggles up with mom during her first weeks at Zoo Atlanta in 2006. 

Photo: Zoo Atlanta

(Below) Mei Lan strikes a postcard worthy panda-pose.

Photo: Atlanta Zoo 

(Below) The Washington Post shares video of Tai-Shan's last days in DC. 

Tai-Shan received farewell letters from DC area students including this one from Florence Kane, age 8.