Further information can be found at https://www.prisonhistory.org/lockup/barmouth-roundhouse/
Descriptions
'History: Built on the instructions of the county's magistrates as a lock-up for drunks and petty offenders. The building contract was given to Thomas Rees, Jones James and Rees Owen of Dolgellau and is dated 12th November 1833; their fee was ú55.
Exterior: Single storey; circular plan. Of rough dressed stone with aconical slate roof rising to a central cylindrical moulded stack. There are 2 rooms, each served by a plain flat-arched entrance with 2 barred slit-windows flanking and set high up.
Interior: Within each room is a corner privy and presumably a fireplace (this latter feature is currently obscured: autumn 1994).'
British Listed Buildings, 'Ty Crwn (The Lock-up), Barmouth', CADW 4898
'This unusual building was constructed to lock-up the drunks and ne’er-do-wells that must have frequented a busy port like Barmouth. It was built in 1833, at the orders of the local magistrates, to a circular design so that the Devil would have no corners to hide in! The space was divided into two halves by a curtain wall to enable the holding of male and female drunks separately.
There are newspaper accounts of people being locked up for merely being without a home for the night – for their own safety! The interior has been partly restored and includes two figures showing what life was like as a prisoner in the 1830's.'
Barmouth Sailors' Institute website (http://www.barsailinst.org.uk/crwn.html)
Sources
Roy's Blog, 'WALES. Lock-ups at Bagillt, Barmouth, Caernarfon, Clynnog Fawr and Hawarden.' (08 July 2013) http://roys-roy.blogspot.com/2013/07/wales-lock-ups-at-bagillt-barmouth.html
British Listed Buildings, 'Ty Crwn (The Lock-up), Barmouth', CADW 4898 https://britishlistedbuildings.co.uk/300004898-ty-crwn-the-lock-up-barmouth#.XQawTbxKiUk
Barmouth Sailors' Institute website http://www.barsailinst.org.uk/crwn.html