Even Ancient Greek children liked building castles by the sea.
ἔρειπε δὲ τεῖχος Ἀχαιῶν
ῥεῖα μάλ᾽, ὡς ὅτε τις ψάμαθον πάϊς ἄγχι θαλάσσης,
ὅς τ᾽ ἐπεὶ οὖν ποιήσῃ ἀθύρματα νηπιέῃσιν
ἂψ αὖτις συνέχευε ποσὶν καὶ χερσὶν ἀθύρων.
(Apollo) threw down the wall of the Greeks easily; just like a sand castle which a child at the seaside builds as a plaything in his childish way but then again destroys with his feet and hands as he plays.