At both Caernarfon Castle and Tintern Abbey, there will only be access to part of the site due to the need for essential conservation or development works.
Dim ond rhannau o safleoedd Castell Caernarfon ac Abaty Tyndyrn fydd ar agor oherwydd yr angen i wneud gwaith cadwraeth neu ddatblygu angenrheidiol.