Facing the eastern wall of the Grand Palace is the yellow-and-white former palace building now occupied by the Ministry of Defense. On the front lawn of the ministry is a sort of open-air museum displaying cannons down through the ages. As many a guidebook once pointed out, most of the cannons were aimed at the Grand Palace. However, a few years ago (in the mid-2000s I think) the cannons were re-arranged so they didn't point at the palace.
The many cannons - which used to be pointed at the Grand Palace - in front of the Ministry of Defense.
The Ministry of Defense is next to the City Pillar shrine. See our Ratanakosin Island map for more location information.