This is 'Epiphyllum oxypetalum' or commonly known as 'Queen Of The Night'.
It is a night-blooming plant and you can find it in South America but this one is from Greece.
I managed to take a photo of the flower.It is a very peculiar plant because the flower blossoms one time per year and only during the night.What is more the flower stays open only for a couple of hours.The flower is very beautiful and smells very nice.
Here you can see it closed:
