By looking at things

From Gus L's review of C1 Hidden Shrine of Tamoachan:

"Yeah this whose place feels realish, there's an ancient culture behind this fun house, and the player and GM can get a feel for that.  There are a lot of things to discover that show the why and how of the place without really impacting play (except as delays for the dumb 1D6 turn poison gas mechanic). The best party of old style games is that they encourage exploration instead of combat, and by looking at things, interacting with stuff and pawing about the players (ideally) get a novelistic or even cinematographic sense of place and scene from their being some visual and environmental cues to hang thier imaginations on."

Emphasis added for something to which we should aspire when writting any adventure.