Forge of Fury Mountain Door map question

Hey folks, I am prepping Forge of Fury and on the Map of the "Mountain Door." The cliffside south of the entrance, there is a large 20 foot circle. There is no description of what this is. I find this bizarre. It is clear it must have been once a guard tower. Am I wrong? Did I miss what it is? Is it ruins? The only thing in the description that might be referring to it is this:

"Up ahead, the path opens onto a wide ledge and then doubles back sharply into the mountainside." It seems like a poor description of a perfectly round 20' area, south of the entrance....

Thanks...it will be described as ruins of a once tall guard tower, so no biggie...

I was wondering this as well.  Then I saw on a youtube run-through that they simply used it as the “start here” spot.

The circle being the starting point makes sense based on there being a ledge but there are marks on the map that look like trail going straight into the entrance of the cave. Very confusing but I like the idea of using the 'ledge' as the start so the party needs to turn the corning to get into the cave.

Quote from clear_seeker >>

Hey folks, I am prepping Forge of Fury and on the Map of the "Mountain Door." The cliffside south of the entrance, there is a large 20 foot circle. There is no description of what this is. I find this bizarre. It is clear it must have been once a guard tower. Am I wrong? Did I miss what it is? Is it ruins? The only thing in the description that might be referring to it is this:

"Up ahead, the path opens onto a wide ledge and then doubles back sharply into the mountainside." It seems like a poor description of a perfectly round 20' area, south of the entrance....

Thanks...it will be described as ruins of a once tall guard tower, so no biggie...

 The circle likely indicate the PC's starting location. The original 3E version of the map also had this nondescript circle.

The description of the wide ledge is the elbow further ahead right before the cleft. The layout described before it is;

The path climbs up one last steep switchback toward a bare shoulder of rock. The hillside rises steeply on your right and drops away precipitously on your left.