  We shall investigate a flipping contraction g : X -> Y from a 4-fold X with
at most isolated complete intersection singularities. If Y has an
anti-bi-canonical divisor (=bi-elephant) with only rational singularities, then
g carries an inductive structure chained up by blow-ups (La Torre Pendente),
and in particular the flip exists. This naturally contains Miles Reid's
`Pagoda' as an anti-canonical divisor (=elephant) and its proper transforms.
