The Cross of Cong (Irish: Cros Chonga, "the yellow baculum") is an early 12th-century Irish Christian ornamented cusped processional cross, which was, as an inscription says, made for Tairrdelbach Ua Conchobair (d. 1156), King of Connacht and High King of Ireland to donate to the Cathedral church of the period that was located at Tuam, County Galway, Ireland.

[2] In addition to traditional Irish design features from Insular art, the cross also displays some Viking and Romanesque influences,[1] including 'strapwork' decoration in the Urnes style.

The reincarnation of centuries-old Irish metalworking techniques, such as the juxtaposition of red and yellow enamel, is seen on the Cross of Cong and Manchan shrine.

The translated Irish language inscriptions read as follows: "A prayer for Tairrdelbach Ua Conchobair, for the King of Ireland, for whom this shrine was made.

Pray for Domnall mac Flannacáin Ua Dubthaig, Bishop of Connacht and Comarb [Successor] of [Saints] Comman and Ciaran, under whose superintendence the shrine was made.

[5] The Latin inscription occurs twice – once on each side of the shaft – in one case the letters of the sixth word are PAHUS, and in the other, PASUS; it should read PASSUS.

[10][11] The cross was likely commissioned by Bishop "Domnall mac Flannacain Ui Dubthaig", of Elphin,[citation needed] one of the richest episcopal see's in Medieval Ireland,[12] and created by the master gold-craftsman named Irish: Mael Isu Bratain Ui Echach ("Mailisa MacEgan"), whom O'Donovan says was Abbot of Cloncraff, in county Roscommon,[13][12] though firm evidence for this identification is lacking.

In the annals, the cross is sometimes called in the Irish language "an Bacall Buidhe", which translates as "the yellow staff" – a reference to its golden colour.

[16] According to the Irish annals, a small piece of the purported True Cross arrived in Ireland in 1123 and was enshrined at Roscommon.

In later centuries, the exact location of the cross in the Cong area is uncertain but it appears to have been hidden by locals and ecclesiastics in their homes because of religious persecution against Catholics, which reached its peak in Ireland under the penal laws.

[17] In the 19th century, George Petrie, the Irish antiquarian, was aware that Lhuyd's book mentioned the cross, though he partly misinterpreted the details.

Prendergast had discovered the cross hidden in an old oak chest kept in a house in the village, where it was said to have been kept since about the mid-17th century (the time of the Cromwellian conquest of Ireland).

Prendergast's possession and stated that at that time (the early 19th century) the cross was used at Cong chapel at the festivals of Christmas and Easter, when it was placed on the altar during mass.