One such is Fort William and I must confess I was just going to write about who gave his name to the fort which no longer exists at this town in south west Inverness-shire. But when I started researching this post (by which I mean 15 minutes googling) I discovered - news to me - that parts of the fort still exist.
There it is on the latest edition of the OS 1:25,000 map - I've never seen it marked on any previous OS map:-
I also found this picture of the remains of the fort on the Royal Commission for the Ancient and Historical Monuments of Scotland website
It's the roughly oblong green bit between and below the two roundabouts. Next is a photo of the walls of the fort from Geograph:-
The remains of Fort William are certainly not on the Historic Scotland trail and, as I say, I'd no idea there was anything left of it to see and apologies to anyone who's well aware of its continued existence.
This is the history. You've heard of the English Civil War in the 1640s when Parliament took up arms against King Charles I, right? In England, the gripe was the king's high handed attitude to levying taxes. But there was a also parallel civil war in Scotland in which the king's enemies - called the Covenanters - had a gripe about his religious policies. Long and short is Oliver Cromwell got fed up with all of them, closed down Parliament, executed the king (1649) and invaded and conquered Scotland (1651).
The Highland clans had been particularly active in Scotland on behalf of the king so, in 1654, one of Cromwell's key generals, General Monck, established a fort at the strategic location which is now Fort William but was called Inverlochy at the time. When King Charles II was restored in 1660, the fort at Inverlochy was abandoned but it was rebuilt in 1690 and renamed "Fort William" in honour of King William III (aka "William of Orange"). This was in the context of the overthrow of the Catholic Stuart King James VII & II in 1689 and the beginnings of the Jacobite rebellions which sought the restoration of the Stuart dynasty and in which the Highland clans were once again particularly active.
Fort William was besieged during the rebellions of 1715 and 1745 and reconstructed after the latter. However, part of the north rampart was destroyed in a flood in the late 18th century and, as peace had returned to Highlands by then, it was not repaired and abandoned as a military garrison. The picture below shows the fort around the 1880s by when it was in private ownership:-And this is how the Ordnance Survey 25 inch scale map shows the fort in 1871:-
The end of the line for the fort came in the 1890s when it was bought by the West Highland Railway and mostly demolished to accommodate a goods yard in connection with the new railway into Fort William. Needless to say that goods yard is now occupied by a Tesco.
This last picture is also from the RCAHMS website. I'm not sure of the date but it looks early 19th century before the railway (or Tesco) and shows the fort to the left with the small village which grew up around it originally called Maryburgh in honour of Queen Mary, joint monarch with the eponymous King William.