The town and castle were built on a curiously shaped rocky eminence which commanded the entrance to the valley, leading to the heart of the Island.
Cronk with its strategic position became a fortified town at an early date, but the castle is relatively late. It is a development of a much earlier Celtic Peel or Refuge Tower. It was built in 1104 by Sigmund, the first King of an independent Sodor. He pulled down the Peel, and replaced it with a Norman type motte and bailey.
During the Great Rebellion Cronk, having been promised Irish help via Harwick and Peel Godred, held out for four months against Cromwell; but the relief never came, the garrison surrendered on honourable terms, and the castle was blown up. The ruins are in the care of the Sodor Island Trust.
The town is a busy one but has no big employer. There are instead a largenumber of smallfirmsall engaged in light electrical industry or instrument making of one form or another. Cronk is a fascinating town, and an ideal centre from which to explore the Island. It has a number of good hotels of which The Crown of Sodor in Sigmund Street is considered the best.
Just to the west is a magnificent viaduct where Gordon once had his dome blown off in 1957. A few miles to the north is a public school and the ruins of Cronk Abbey, both of which are serviced by Abbey Station on the Peel Godred Branch Line.
It was first seen in the Railway Series book Stepney the "Bluebell" Engine where Gordon takes over the train from Duck and Stepney. It later appeared in Enterprising Engines where Flying Scotsman and Donald take over the failed diesels' trains from Henry.
In the television series, it made an appearance in the sixth season episodes, A Friend in Need and Jack Jumps In and in a Jack and the Sodor Construction Company episode, Mud, Glorious Mud, as well as an eighth season learning segment, How Does Emily Get to the Station? and the song, Navigation. It was mentioned in the Jack and the Sodor Construction Company episode, A Happy Day for Percy and the seventeenth season episode, Gordon Runs Dry.
- A siding was added only in the eighth season learning segment, "How Does Emily Get to the Station?" and in Jack and the Sodor Construction Company, a car park was added.