Alysos (), also known as Altsos (ÃÂûÃÂÃÂÿÃÂ) or Alsos (ÃÂûÃÂÿÃÂ), is a rock in the Meteora rock formation complex of Thessaly, Greece. The rock overlooks the eastern side of the town of Kalabaka.
The Monastery of the Apostle Peter's Chains (Alyseos Apostolou Petrou, ÃÂûÃÂÃÂõÃÂàÃÂÃÂÿÃÂÃÂÃÂûÿààÃÂÃÂÃÂÿà) on Alysos Rock was probably built around 1400. The ruins () can still be found on the rock today. In full, the monastery is known as the Monastery of the Veneration of the Chains of the Apostle Peter ().