PC Gamer reports that the ESO-expansion Clockwork City will be available on October 23:

The Elder Scrolls Online Clockwork City release date announced

The brass fortress awaits.

The Elder Scrolls Online is heading to Sotha Sil's Clockwork City for a ten-hour expansion, due out on October 23. The update is included as part of the ESO Plus membership, and otherwise costs 2000 crowns in the in-game Crown store. That's roughly $20 / £15 worth of crowns once you've converted the amount from real money.

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Thanks Henriquejr!