https://www.timesofisrael.com/mossad-agents-snuck-nuclear-files-out-of-iran-with-authorities-on-their-tails/A very good read:
The warehouse storing the files was located in the Shorabad suburb in southern Tehran, in an industrial area. Mossad discovered the warehouse in February 2016, and had had the building under surveillance since then. Before arriving at the site, the secret archives had been moved by Iranian authorities several times in a bid to keep their whereabouts a secret.Updated May 2, 2018, 10:22 PM