Renowned Scottish architect William Young first started on the design of The Old War Office in 1898, but the project was taken over by his son, architect Clyde Young, when William died in 1900.

The building took five years to build and cost £1.2 million. The building spanning 580,000 sq ft with 1100 rooms set over 7 floors and 2.5 miles of corridors was finally completed in 1906.

Photo credit: Imperial War Museum via theowo.london