The Bronze Age was gradually superseded by a period influenced by a new metal – iron. The use of iron spread from Europe and could be made into efficient tools and weapons. The many forts dotted around the promontories of the island typify the Iron Age on Bute. These people had power and possessions and went to great lengths to defend themselves from the very real possibility of attack.
The most important Iron Age site on Bute (and one of the finest sites of this period in Scotland) is at Dunagoil at the south end of the island. The fort at Dunagoil is perched high on a volcanic cliff with clear views of the seaways around Bute. High stone and timber walls would have surrounded the fort and at some point these walls burned with such intensity that the rubble core became fused into a solid mass (known as vitrification).
The fort was excavated by Ludovic Mann about 100 years ago and the huge amount of artefacts he discovered showed that the fort had been an important one. One of the areas was found to be used for metal working . In this area were found metal objects, crucibles, moulds and metal slag. The crucibles had been used for melting copper alloys and one may have been used for recycling scrap metal of Roman origin. Two of the moulds found are for the manufacture of spear butts.
Artefacts on display in the museum illustrate all facets of domestic life at the fort. Spindle whorls and a weaving comb show that yarn was being spun and woven. There is daub from houses, stone and pottery vessels, tools of stone and antler, large amounts of lignite jewellery, including a finely carved bangle. One very rare find was a bone whistle with carved decoration.