In the front lawns of the building, arranged in a garden display, are a large collection of bronze cannons.
The display was initiated by King Vajiravudh (Rama VI, r. 1910–1925), who was probably inspired by his experience at the Royal Military College, Sandhurst.
Sixty-three guns were once displayed on the lawn, according to a 1921 survey, but many have been relocated and forty currently remain.
Almost all of the cannons bear inscribed names, such as "Uprooter of Phra Sumeru" (ถอนพระสุเมรุ) and "The Wind that destroyeth the Earth" (ลมประไลยกัลป์).
The largest and most famous is the Phaya Tani, which was captured from Pattani (then capital of the Pattani Kingdom) in 1786.

The display has been reorganized many times.
In 2004, several guns including the Phaya Tani were rotated to face the building, prompting rumours that the ministry was trying to avoid bad luck resulting from the guns pointing towards the Grand Palace, as they had previously done, in an attempt to alleviate the South Thailand insurgency.
This was denied by ministry permanent secretary General Oud Buangbon, who said that it was part of a re-landscaping project, done in accordance with a request from the Ministry of Tourism and Sports and advice from the Fine Arts Department, and also to mark the ministry's 120th anniversary.

The display has since been reorganized again, so that all the guns now point sideways.
In 2014, the ministry inaugurated the exhibit as an outdoor museum, titled the Ancient Artillery Museum, with information placards and scheduled guided tours.
The garden also features two large gajasiha statues and musical fountains.
In the front lawns of the building, arranged in a garden display, are a large collection of bronze cannons. The display was initiated by King Vajiravudh (Rama VI, r. 1910–1925), who was probably inspired by his experience at the Royal Military College, Sandhurst. Sixty-three guns were once displayed on the lawn, according to a 1921 survey, but many have been relocated and forty currently remain. Almost all of the cannons bear inscribed names, such as "Uprooter of Phra Sumeru" (ถอนพระสุเมรุ) and "The Wind that destroyeth the Earth" (ลมประไลยกัลป์). The largest and most famous is the Phaya Tani, which was captured from Pattani (then capital of the Pattani Kingdom) in 1786.
The display has been reorganized many times. In 2004, several guns including the Phaya Tani were rotated to face the building, prompting rumours that the ministry was trying to avoid bad luck resulting from the guns pointing towards the Grand Palace, as they had previously done, in an attempt to alleviate the South Thailand insurgency. This was denied by ministry permanent secretary General Oud Buangbon, who said that it was part of a re-landscaping project, done in accordance with a request from the Ministry of Tourism and Sports and advice from the Fine Arts Department, and also to mark the ministry's 120th anniversary.
The display has since been reorganized again, so that all the guns now point sideways. In 2014, the ministry inaugurated the exhibit as an outdoor museum, titled the Ancient Artillery Museum, with information placards and scheduled guided tours. The garden also features two large gajasiha statues and musical fountains.
Ministry of Defence headquarters (Thailand)