Constructed between 1917 and 1921, the 216 feet tall Harkness Tower is a masonry tower that serves as a symbol of Yale and New Haven. There is an interesting fact about the height of the tower. Yale was founded in 1701 and after 216 years, the tower was completed in 1917, which means one foot for each year since Yale's founding at the time it was built. It was the first-‘couronne’ or crown tower in English Perpendicular Gothic style-built in the modern era. The tower and the Memorial Quadrangle were donated to Yale by Anna M. Harkness in the memory of her deceased son Charles William Harkness, an 1883 Yale graduate and brother of Yale's largest benefactor, Edward Harkness. An inscription near the door to the bell tower indicates that the original ten-bell chime in this tower was also donated by Mrs. Harkness in 1921, as a part of the memorial. Later, in 1966, Miss Floren S Marcy Grofut donated the additional forty-four bells in memory of her parents. Nevertheless, after the inauguration of the residential college system, the tower became a part of Branford College.

The Harkness Tower was designed by James Gamble Rogers, who also designed many of Yale's Collegiate Gothic structures. Roger was a Yale College classmate of Edward S. Harkness, another son of Anna Harkness. According to Rogers, his design for the Harkness tower was inspired by ‘Boston Stump’, a 15th-century tower of St Botolph Church in Boston, England, which was considered as the tallest parish church tower in all of England in those days.

The Harkness tower rises in stages, from a square base to a double stone crown on an octagonal base, dissolving at the top in a spray of stone pinnacles. From inside the tower, 284 winding steps go up nine storeys.

The middle part of the tower is decorated with four beautiful blue clock faces, one on each side. The bells of the carillon are located behind the clock faces, fixed to a frame made of steel. The playing console of the carillon is situated at the level of the balconies immediately below the clock faces. The student-run Yale Guild of Carillonneurs and the selected guest Carillonneurs play the Carillion for two half-hour sessions per day during the academic year. Lower levels of the tower contain a water tank, which is no longer in use, two practice carillons, the old chimes playing console, office space for the Yale University Guild of Carillonneurs, and a memorial chapel.

The decorative elements of the tower were sculpted by Lee Lawrie, a Yale professor from 1908-1918. The sculpture in the lowest level of the tower depicts Yale's Eight Worthies. The next level of sculpture includes depictions of Phidias, Homer, Aristotle, and Euclid.

The last level consists of depicting allegorical figures, which include among others, Justice, Truth, Medicine, Business, Law, Freedom and Courage. The waterspouts on the top level depict Yale's students at war and in the study along with masks of Homer, Virgil, Dante, and Shakespeare.

A renovation project for the Harkness tower was undertaken from September 2009, to repair its masonry and ornament and the project was completed in May 2010.