It involves a very prominent circle that you probably already noticed at some point.

You have to get to a higher spot to solve it.

You'll be looking downward as you solve it.

Symbol #3 is drawn from the top of the building with the stairs and the scaffolding -- the one with that black panel-looking thing you can rotate.

Climb up there, stand by the rotateable thing, look down at the black hole, and you'll quickly see how to draw the path.

The circle is the big black hole above the Projector room.

From the correct spot (and height), you can combine it with those black wall fragments to make a path.

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You see this while you're in the Town area.

The circle itself is just to the west of Town, but when you solve this, you'll be back in Town.

There are actually a few high places in Town that allow you to trace the paths for three different symbols -- symbols #2, #3 and #4 on this North face of the obelisk.

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