Every class gets a tour of the high-speed rail construction sites, where they see up close the viaducts and girders that are being put up every day.

Scanning the rubble, Ali caught sight of a pink, soot-covered pair of girls’ tracksuit bottoms, hanging from a steel girder jutting out of the heap.

The final box girders were swung into place at the end of 1963, covered in the Union Flag and Lion Rampant to mark the occasion.

Installation of the steel girders were completed back in April, and crews have since been assembling wood forms and placing reinforcing rods in preparation for concrete pouring.

Last week, the final girder was installed on the crossing, completing the foundation and marking a construction milestone.