Build it up

There is a song that the folks on Play School (Lily's favourite show) sing when they are building with boxes:

Build it up, build it up, build it high
Build it up, up, up into the sky
Build it up, build it up, build it higher
Build it up up up up up into the sky

She's taken a real liking to building castles with me. We can only do this in the few hours that Lukasz naps each afternoon, because within minutes of his arrival on the scene, the castle is invariably reduced to rubble.