Following a severe drop, a diagonal girder in ring 17.5, which supported the forward fin attachment points, failed.

The towers consist of galvanized steel parts, which are hold together by a network of diagonal girders.

The windows sit in the facade like flattened amoebas; inclined supports and diagonal girders seem to have jumped straight from the computer screen into reality.

Most of them were above Ace and Defries, fluttering round the diagonal girder along which Daak was trying to climb.

Ace looked up, tracing a route from the stanchion to a diagonal girder, an almost vertical cable, a narrow pipe and then a short piece of wider ducting.