Fyanstown is located two miles from Kells on the road to Slane/Drogheda. The townland is split between tow parishes – there are 427 acres in Kells civil parish while there is 53 acres in Donaghpatrick civil parish. The Donaghpatrick section was known as ‘Back Lane’ in the 1830s and had been recorded as Jackestown in the seventeenth century surveys.  The neighbouring townland of Bloomsbury is similarly divided between the two civil parishes.  In the 1836 map the ruins of a castle is marked on the map. A ring fort near the Blackwater still survives to this day. In that year both portions were in the possession of the Marquis of Headfort.

According to O’Donovan the Irish name for the townland is ‘Baile Fhideán’ meaning the town of the Fyan family. The Fyans were important citizens in Dublin the fifteenth and sixteenth centuries. The family seems to have had connections to the Butlers of Dunboyne. Richard Fyan was mayor of Dublin in 1549 and 1564. His only daughter, Anne, married Richard Barnewall, 5th Lord Trimlestown.  A Walter Fyan was mayor of Drogheda in 1619. The townland of Finnstown in west Dublin is said to derive its name from the family. Finnstown House, a celebrated country house hotel, in the townland was developed by Eoin Hickey, whose mother lived at Skryne castle and was heavily involved in local history.

The FitzJohn family are the first family noted at Fyanstown Castle. Patrick Everard married Catherine, daughter of Thomas FitzJohn and the family settled at Randlestown. About 1560 James Plunkett, Baron Killeen, married Margery Fitzjohn (or Fitzgerald), daughter of Richard FitzJohn of Fyanstown. In 1598 FitzJohn of Fyanstown was required to supply one armed horseman for the defence of Meath, if requested. James FitzJohn of Fyanstown appears to have been disposed by the Cromwellian settlement. In 1664 he applied to recover his lands as he had adhered to the peace treaty of 1643 and lived at home quietly and at peace since that date.

The Attainders of 1641 present the names of Richard and Patrick Magrath, both of Fyanstown, County of Meath. In the list of outlaws 1641-47 yeomen Patrick and Richard McGrath, Fyanstown and William Seagard, yeoman of Fyanstown are listed.

Lucas Everard of Fyanstown, was attested for being a member of King James’s army after the Battle of the Boyne.

Darcy Wentworth arrived in Ireland as an agent in Athlone to Wentworth Dillon, fourth earl of Roscommon. Settling near Trim he served in the army of William III and established himself as a landowner at Fyanstown. Darcy Wentworth obtained a lease of Fyanstown in 1692. His son, George married Catherine Longfield of Kilbride, Trim. Their son, Robert, was under-age when his father died and later moved to Bride Street, Dublin. Robert, a barrister with political ambitions, married Mary Walsh in 1731 and was succeeded by his eldest son, Darcy Wentworth. The lands were mortgaged in 1730 and eventually sold in 1742. Darcy Wentworth, Esq., was living near Portadown, co. Armagh, 1747, and in Portadown, 1801. A nephew of Darcy’s was Rev. Wentworth Sheilds,  rector of Kilbeg and Newtown, co. Meath. From this time the family seem to have been connected to Portadown and Dubliun. A branch of the family became established in Australia when a Darcy Wentworth went to the colony in 1791 as superintendent of prisoners. He had escaped hanging, having been three times tried for the crime of highway robbery. He went on to be promoted to various positions in the colonial administration, dying at Home Bush, Parramatta, New South Wales on 7th July, 1827. His descendents played significant roles in the political and military fields in Australia.  

The Barnewalls of Trimlestown became important in Fyanstown in the eighteenth century. Christopher Barnewall, born 1715 and married 1764, was the first of the family to be noted from Fyanstown. His only daughter, Anne, of Fyanstown castle, married Columbus Drake of Roristown, Trim in 1777. His second son, Richard, married Katherine Byrne of Seatown. Their son, Christopher, became established at Bloomsbury.  In Catholic convention 1792-93 Richard Barnewall gentleman of Fyanstown and Bloomsbury represent Co. Meath. This convention, meeting at Tailor’s Hall, Dublin, called for the relaxation of a number of the Penal Laws. The title of Lord Trimlestown was to descend to the Barnewalls of Bloomsbury in 1879 on the death of the existing lord, a distant relative.

Today there is no trace of Fyanstown Castle.