Introduction to the Triangle Clock: The Triangle Clock is located between the Administration Building and the Great Lawn. It is a small white triangular pillar with a clock on the top. It was jointly donated to the school by the alumni of the Class of 1921 on the 60th anniversary of Tsinghua University; The clock above was donated by Chai Zhidi, an alumnus of the class of 1944, to celebrate Tsinghua University’s 70th birthday.