Map-maker John Slezer's work gives us a picture of a long-gone scotland VISITORS to Edinburgh may need a map to navigate the city's complicated streets but in the 17th century maps were vital political tools. The current exhibition of maps by John Slezer at the Scottish National Portrait Gallery might make you think again when you open an A to Z. John Slezer was an ordnance engineer of German origin who came to Scotland in 1669 to survey fortifications and defences and draw up military plans for the Army. The government of that era took map-making very seriously: the documentation of the British Isles meant having the power to challenge rebellion or invasion. In fact, the Ordnance Survey maps so beloved of hill walkers today have their origins in those maps used by the military as tools of war, and formerly stored in the Tower of London. During a 20-year period Slezer created maps and drawings which were both visually and historically compelling. His book Theatrum Scotiae contains the earliest comprehensive mappings and views of Scotland. It is a fascinating and detailed record of the built landscape at that time. His engravings of Edinburgh were celebrated for their accuracy. Slezer made incredibly meticulous views of the city using a camera obscura, an advanced technology at that time. He used a pin-hole camera to capture an accurate outline of the city which was then translated into engravings by his assistants. Looking at these beautifully detailed maps, it is obvious how much the city has evolved over the past 300 years. The historical maps and geographical descriptions in Theatrum Scotiae give amazing insight into Edinburgh life at the time. Slezer created documents which were to be of incredible value to future generations in tracing the history of the city, but in his own lifetime he ran into trouble on several occasions. In 1687 Slezer had been promoted to Captain of the Scots Train of Artillery, an important military position, but in 1688 when James VII was deposed from his throne by William and Mary, Slezer was incarcerated as a rebel supporter, only being freed when he swore allegiance to the new regime. Slezer went on to publish the first edition of Theatrum Scotiae in 1693. Disastrously, sales of the volume were slow and increasing financial pressures mounted. Monies promised by the government were not forthcoming and when he died in 1717 his last will and testament stated he was an "indweller in the Abbay of Holyroodhouse" - the old Abbey traditionally gave sanctuary to debtors from their creditors. He died penniless in his adopted homeland but his sharp eye and meticulous work left us a treasure: a testament to the great changes which have swept Edinburgh in the past three centuries.