landmark (n.)

• bookmark
• cairn
• climax
• core
• cornerstone
• crisis
• crux
• essence
• essential
• feature
• fundamental
• gist
• guide
• guidepost
• heart
• identification
• issue
• kernel
• keystone
• lighthouse
• lightship
• major
• mark
• marker
• meat
• menhir
• milepost
• milestone
• monument
• notable
• nub
• pharos
• pith
• pivot
• platform
• substance
• tower
• watchtower
• watershed