Gravesend Grammar School was opened by Princess Beatrice, youngest daughter of Queen Victoria, on 19 July 1893 with due pomp and ceremony. The school was originally based in Darnley Road, Gravesend and later moved to the site of Milton Hall, the former home of Mayor G. M. Arnold JP, one of the school's founders. The original building is currently used as an adult education centre. The replacement building, erected between 1931 and 1938 and officially opened on 12 October 1938, is still in use. Although many alterations and additions have been made to it since it was originally constructed, including being partly rebuilt after being bombed during World War II, having been mistaken for Eton College.
A second school building, known as the Centenary Building, was built in 1993 to commemorate the school's 100th year and currently houses facilities including multiple computer facilities and chemistry labs. There are a number of mobile classrooms around the school site, used for various subjects, although these are beginning to be replaced by more permanent buildings.
In July 2009 a new sports centre was opened, adjacent to the sports hall, and named the Sanderson Sports Centre, after a former headmaster. Overall, there are 63 classrooms, including six computer rooms, all of which contain interactive whiteboards, as well as a library, a sports hall, several small music practice rooms and a canteen available to all staff and pupils. In 2013 the main school and the Centenary Building were linked by a new building containing eight new classrooms including a large art room and a lecture theatre. In 2016, a new music block was opened opposite a computer facility. This new music block has many new features and is a vast improvement on its predecessor. There are 3 practice rooms, a recording studio and a main room for clubs and other musical activities.
In 2004 the school gained specialist status as a maths and computing specialist school. This guarantees the school extra government funding in order to continue the running and expansion of its facilities. The school also gained language specialist status, in 2008.
In 2019, A £7 million expansion proposed by Gravesend Grammar School was approved. The new expansion includes:
- A new teaching block for Year 12 & 13 students
- A new Canteen.
This new expansion project would bring the number of new Year 7 students up from 174 to 210 students. Construction of the new Sixth Form block started in 2021 going smoothly. Construction of the Canteen started in March 2022. In July 2022, the project was paused over fire safety concerns because there were no fire hydrants or reliable water supplies. This equipment had to be installed at an additional cost of £900,000. In November 2022, the new sixth-form building opened whilst the new canteen opened in February 2023. On top of the new expansion, minor improvements have been enforced on the main school building, including roof asbestos removal, and new internal windows.