|Founded In||1915 (2nd Floor: 1971)|
|Founder||Rev. E.E. Benson|
Student Dormitories, Recreation
This building was not named after a Lord Bishop of Calcutta and hence there was a departure from the tradition in naming school buildings. The First floor has the Lyon Hall dormitories. In 1971, during the time of Mr D.S. Gibbs, a second floor was added named Centenary Hall which replaced Milman Hall with its iconic balcony overlooking Top Field as the Senior most Dormitory of the school.
Ground floor serves a different purpose altogether from the upper floors, being the administrative floor.
The Lyon halls are three dormitories (East, Main and South) on the first floor, with a prefect's cubicle in each dorm. They are occupied by students of class 9 and 10 only. Of the three, Lyon Main is the biggest and also faces the Quadrangle. A Master's quarter is also present towards Lyon South Dorm, as well as the Stationary supplies room. A steep staircase leads up to the Centenary Halls.
The Centenary (Cent) dorms are on the second floor for students of classes 11 and 12. These Dormitories were created in 1971 replacing Milman Hall as VI Form Dormitory (Class 11 was the senior most class in school those days) with an individual cubicle for each boy for the first time. Because the floor was added over 50 years later, there does not seem to be the use of rock bricks in its construction and a distinction (though blending with old architectural design) can easily be made of the later addition from outside. The individual student cubicles in the dorms (Cent East and Cent West) have now been removed and instead, there's one cubicle per dorm only for prefects. Adjacent to the dorm are the Rahoul room and the Geography Lab, as well as a Master's residential flat.
- The original purpose of Rahoul room was an exam centre from right from December 1971 till as recent as 2005.
- The present MCR was the Physics Laboratory until 1983, when it was shifted to Lefroy ground floor.
- The present Lecture Hall was the Chemistry Lab until 1983.
- Earlier, the rector's office was where the present waiting room is. Before, the waiting room, there was the senior wing stationary at its place, which was relocated to the MI room, where it occupies a part of the room and is accessible from Quad side.
- During 1968 - 1971 Lyon Hall (East) was known as Lyon Hall (North). Same with Cent (East).
- Lyon Hall (South) became a dormitory only around 1957. Earlier this was the Art and Woodwork Room, presided over by Mr Rathin Mitra, then by his successor Mr Munshi during whose tenure in 1957, art room was shifted to the Building on the School's main drive (Wood Carving hobby), which is now called Old Art Room, since art Room was shifted again (to its present location).
- In 1971, when Centenary Hall was built, between this Room and the one Next Door, one was a VIth Form Common Room and the other was a Prefects Common Room.
- During the later half of 1990s, before the Building of Howard Block, the computer room was located in Cent (East). Computer Science was offered as an optional subject and there was a Hobby as well (people would design basic games, etc).