Once all visits are completed, passport holders can enter a special prize draw to win two free National Trust family day passes and wireless Bluetooth headphones.
Unwaith y bydd pob ymweliad wedi'i gwblhau, gall deiliaid pasbort gymeryd rhan mewn raffl arbennig i ennill dau docyn diwrnod yr Ymddiriedolaeth Genedlaethol i'r teulu a chlustffonau Bluetooth diwifr.