Learn to sing from the best: the Welsh National Opera

Question

They will teach us an old Czech round.

(We used to sing this in grade school.)

But the second verse went:

But no, 'tis not a young boy's head,

'Tis Ifca's castle there instead.

A-hooya, hooya, hooya-ya,

Swiftly flowing river.

And the explanation (which I never knew before) is here:

https://danaxtell.com/ifca/

Answer 1