countryside disused estuary exercise footpath forest green landscape line Mawddach natural nature path peaceful railway river track trail tranquil view wales walk water welsh attention beware black danger directions forbidden isolated passing pictogram platform rail red security sign station train trains transport transportation triangle warning yellow refreshing shadow sunlight trees baby boy bridge car child childhood children drive engine game imagination kindergarten little play playschool preschool pretend railroad set small sunday school toy wooden bilingual english german Multilingual plate architecture blocks buildings city cityscape England Great Britain landmarks London London Eye shard skyscraper thames tower urban wheel amsterdam building composite engineering fixture holland hub material metal modern passengers public transport rails rolling roof stock The netherlands travel voyage marsh walkers