Cafodd y cam cyntaf i efeillio'r ddau safle, sy'n Safleoedd Treftadaeth y Byd UNESCO, eu cymryd ym mis Gorffennaf 2018 pan fu Maer Himeji ar ymweliad â'r Gogledd a phan ymunodd â Maer Conwy i lofnodi Memorandwm Cyd-ddealltwriaeth ‒ y cyntaf o'i fath yn y DU. Bydd dirprwyaeth o Gonwy yn bresennol mewn seremoni swyddogol yn Himeji heddiw ac yn llofnodi Cytundeb Cydweithredu er mwyn selio'r broses efeillio.
The first step towards the twinning of the 2 UNESCO World Heritage Sites was taken in July 2018 when the Mayor of Himeji visited north Wales and joined the Mayor of Conwy to sign a Memorandum of Understanding — the first of its kind in the UK. A delegation from Conwy will today attend an official ceremony in Himeji and sign a Co-operation Agreement to seal the twinning process.