The classic 6.7 km Penteli loop with views over Attica and Evia, mostly on marked forest paths plus forest road and asphalt: Profitis Ilias, Agios Nikitas, Agios Loukas church, the Aloula old marble quarries, the open-air marble museum, the Solinari spring, the marble-carved map and the sculpture park. 1.5 km climb on a narrow forest path at the start. +281/-281 m, altitude 425-686 m. Grade 1+: hiking shoes and a waterproof needed; springs are likely dry, so bring water. Meet 09:00 at Chloridon 24, Drosia, start 09:30, back by 13:00. Ages 12-17 with an adult; over-65s under conditions. Fee covers guides, group first-aid kit, photos and video; transport and meals not included. Pay within 3 days of booking; full refund until Sun 6 Dec 20:00, 50% until Thu 10 Dec 20:00.