at devonport, in 1864, a separate, purpose-built steam yard was opened on a self-contained site at keyham, just to the north of morice yard (and a tunnel was built linking the new yard with the old). a pair of basins (8–9 acres each) were constructed: no. 2 basin gave access to three large dry-docks, while no. 3 basin was the frontispiece to a huge integrated manufacturing complex. this became known as the quadrangle: it housed foundries, forges, pattern shops, boilermakers and all manner of specialized workshops. two stationary steam engines drove line shafts and heavy machinery, and the multiple flues were drawn by a pair of prominent chimneys. the building still stands, and is grade i listed; architectural detailing was by sir charles barry. english heritage calls it 'one of the most remarkable engineering buildings in the country'. the three dry docks were rebuilt, expanded and covered over in the 1970s to serve as the frigate refit centre.