The National Museum of Wales traces the tradition back to 1176, when the Lord Rhys held a bardic competition at Cardigan Castle - prizes for the best harpist, the best poet, the best storyteller. Local eisteddfodau persisted through the centuries that followed. Bigger gatherings flared up periodically: the Gwyneddigion Eisteddfod of 1789, the Provincial Eisteddfodau of the 1820s and 30s, the Great Llangollen Eisteddfod of 1858 that drew thousands. But the National Eisteddfod as a continuous institution began in 1861 at Aberdare, with the deliberate aim of becoming the annual centre of Welsh-language culture. It has alternated, when it could, between north and south Wales ever since, planting itself in a different town each year so that no community would be the sole beneficiary - and so that the eisteddfod itself would remain a travelling carnival of Welshness rather than a fixed institution that could be ignored from anywhere outside its walls.

From 1950 onward the rule was made absolute: all competitions take place in Welsh. The only exception is sung settings of the Latin Mass, which has at times let major international soloists onto the stage and at times caused friction. The Welsh-only rule was controversial when it was passed and remains so, but it has done what it set out to do - keep the eisteddfod a place where the Welsh language is the working tongue, not the curiosity. In recent decades the organisers have softened the edge for visitors. The maes, the festival site, offers bilingual signage. Wireless headphones give simultaneous English translation of major events. There is a learners' pavilion called Maes D where Welsh learners can practise without embarrassment. The festival attracts something like 160,000 visitors a year. In 2008 the Eisteddfod at Cardiff drew record crowds; in 2024 at Pontypridd the gate was 186,000.

The Gorsedd Cymru, the bardic order, gives the eisteddfod its visual signature. Ovates in green robes signify spring; bards in blue signify summer; druids in white signify the wisdom of age. The robes were designed in the 1820s by Iolo Morganwg, a stonemason and antiquarian whose enthusiasm for ancient Welsh tradition was sometimes greater than his evidence for it - the ceremonies are largely his invention, dressed in the dignity of antiquity. But invented or not, they have become a real tradition, and a stone circle of Gorsedd stones, taken from the local area, is erected at each festival venue. These circles remain after the eisteddfod has moved on, scattered across Wales like geological souvenirs - in 2005 the festival began using temporary fibreglass stones in the actual ceremony, partly to save costs and partly to bring the ritual onto the maes itself instead of holding it miles away.

Two prizes matter above the rest. The chair is awarded for an awdl, a poem in cynghanedd - the complex, ancient strict-metre system of consonant patterning that has shaped Welsh poetry since the early medieval period. The crown is awarded for a pryddest, a poem in free verse, introduced as a competition in 1867. A new chair and a new crown are designed and made each year, custom pieces by Welsh craftspeople, and the winners take them home. The chairing ceremony is the festival's emotional centre. A trumpet calls. The presiding bard rises and recites in Welsh: A oes heddwch? Is there peace? The crowd responds: Heddwch. Peace. The cloth is lifted from the chair. The winner is named. If they are present, they walk forward to be enthroned. If they are not, the chair stays empty - and people remember 1917.

Beyond the ceremonies, the maes holds dozens of pavilions across eight days. The Pabell Len for literature. Y Lle Celf for art. The Pabell Wyddoniaeth a Thechnoleg for science. Maes B for late-night music. Hundreds of stalls sell crafts, books, food and the cause of every Welsh society, party, charity and chapel. Since 2004 alcohol has been sold on the maes; before that the eisteddfod was officially dry. The 2018 Cardiff festival broke another tradition by holding itself in the permanent buildings of Cardiff Bay rather than on a vast green field of tents, billed as the Eisteddfod with no fence. The 2020 festival was cancelled by COVID - the first time since 1914 - and replaced by Eisteddfod AmGen, an online alternative held remotely. By 2022 the festival was back on actual fields. The next year it visited Boduan in Gwynedd. It will not be the same field twice. That, in the end, is the point of the thing.