Need a hint?
What beautiful postcards. Take some time to read about the various places.
In each postcard there is something that stands out. Pick these out for each postcard. I wonder what order they go in?
The stamps hold the key to the order. Dolbadarn Castle - pick out the blue letters, Ffestiniog Railway - pick out the underlined letters, Llyn Padarn - list the missing letters, Snowdonia National Park - pick out the bold letters.