Inchgarvie or Inch Garvie is a small, uninhabited island in the Firth of Forth. On the rocks around the island sit four caissons that make up the foundations of the Forth Bridge. Inchgarvie's fortifications pre-date the modern period. In the days when boats were the only way to cross the Firth of Forth, the island was on the main route between North Queensferry in Fife and South Queensferry in Lothian. This made it strategically important. Although now uninhabited, Inchgarvie has been inhabited throughout various periods of history. The first recorded time was in the late 15th century. Like nearby Inchmickery, its profile and colour makes it look like a small warship from a distance. It was armed with coast defence guns from 1901 until 1906, and again from 1908 until the 1930s. Inchgarvie's name is Gaelic in origin and means either "rough island" (from innis garbh) or "island of the rough place" (from innis gharbhaidh). An older theory links it to the Scots word "garvie", which refers to the sprat. A commercial sprat fishery took place in the inner Forth until it was prohibited in 1983. Records of Danish attacks on nearby islands, particularly Inchcolm as well as Fife and Lothian may mean that it was used in some capacity by them. The island was licensed by King James IV to John Dundas of Dundas with the power to build a fort on 20 March 1491. John Dundas did not build the castle, and James IV himself ordered a strong tower to be built in 1513. On 8 March 1514 Margaret, the widow of William Dundas of Dundas, undertook to manage the completion of the fortress that James IV and her father-in-law had begun building on her island. From 23 December 1514, Charles Dennison, Captain of Inchgarvie managed and fed a large royal construction team. The master mason was John of Cumbernauld, with his "servitor" John Strathauchin, who directed eight other masons and ten labourers. Margaret, Lady of Dundas gave them two boats. Two 'serpentine' guns and guns from Colstone were placed on the island after a visit by artillery experts in July 1515, and the island was equipped with a "blawing horne.