After his death in 1863, Dr William Gill, the District Surgeon of Somerset East, left £23 000 to be used to set up and run an institute of higher learning. Farmers and people of the district undertook to fund the building and seven local men, including Robert Hart, were made trustees and given the task of following his wishes. A committee of locals was formed in 1865 to build the school, and the foundation stone was laid in 1867. Gill was opened in 1869, six years after his death. In 1916, his remains were buried in front of the school which he endowed, and which was named for him, Gill College. The magnificent campus is a fitting memorial for such a man.

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The College comprises several buildings, the original college built in 1869 which is now the library, College House built in 1892 is the boys' hostel and the Old Bellevue Seminary which was the girls' high school. The college was established in 1869 as a high school and university training centre for boys. It was originally intended as a university for the Eastern Cape but, owing to strong opposition from the newly formed Rhodes University College, it was unable to meet the regulation that limited university college status to institutions with over 75 matriculated pupils. In 1903 it became a high school only. Gill College was one of the first institutions of higher education in South Africa to admit women.