How a Mariupol steel plant became a holdout for the city’s resistance

As many as 1,000 civilians are also hiding in the subterranean network, Mariupol’s city council said in a Telegram message Monday.

Azovstal was originally constructed in the early Soviet era and was later rebuilt after the Nazi occupation of Mariupol between 1941 and 1943 left it in ruins. It now occupies four square miles along the city’s waterfront.

“Under the city, there is basically another city,” Yan Gagin, an adviser with the pro-Moscow separatist group Donetsk People’s Republic, told Russian state news network Ria Novosti over the weekend.

Gagin complained that the site was designed to withstand bombings and blockades — and that it has an inbuilt communication system that strongly favors the defenders, even if they are far outnumbered.