The original British Secret Service headquarters was just that, secret. But the increase in importance of electronics meant that it was more important for a building to be invisible to electronic eavesdropping. as such the current M16 HQ in London is about as obvious a giant sign saying 'secret building here', yet it is enclosed in a giant Faraday cage to protect its communications.Not all Intelligence agencies have had a discrete architectural past, Franco's House of Screams, or the Soviet Lubyanka are demonstrably terrifying. Mossad's HQ, until the 60s or the current Australian Secret Intelligence Service look quite modest compared to the hardly known Ministry of National Security of Azerbaijan, which houses its intelligence service, in a large and monolithic building of dramatic proportions.