Kathmandu, Aug. 13 -- It was a quiet Saturday morning, and people were lining up for a blood donation drive inside the historic pavilion from which Kathmandu gets its name.

Four minutes before noon on 25 April 2015, the building started shaking. There was a frightening roar as nearby temples collapsed in clouds of yellow dust. Kasthamandap's ancient timber beams creaked and shook, but they could not withstand the force of the quake.

The structure collapsed before the blood donors could scramble out to safety, killing 10 of them. For the past five years this imposing pavilion, built on foundations said to be 1,500 years old, had just been a heap of rubble. But it is finally being restored.

Kathmandu was then on the historic trans-Himala...