Little is generally known of the Royal Arsenal, Woolwich, and the immortal place it holds among all the Royal Ordnance Factories. For nearly four hundred years it was a 'secret walled city', self-sufficient and closely guarded. As it grew, and developed the nation's weapons of war, it became the main source of all implements of war for our armed forces. Even those weapons not produced in the Arsenal very often had to be tested and approved within its boundaries. Here for the first time is a tantalising look behind the walls of the secret city, once among the most sensitive of government establishments.