The lower neck.
The bulk of the thyroid gland lies on both sides of your wind-pipe in your neck.
This area is just above the bony notch at the top of your breast bone. There is a small bridge of tissue that connects the two lobes. Normally you cannot see or feel this gland. See a doctor if this area is puffy, feel like you have something in your throat, or there is a tenderness or fulness in this area.