In what anatomical position of the body is the heart located?

The heart is located behind and slightly left of the sternum, between the two lungs, and enclosed in a sac called the pericardium.

In the human being the heart lies just behind and slightly to the left of the sternum (breastbone) in a double-layered sac called the pericardium.

It is in the thoracic cavity, positioned between the two lungs with the lowest point lying on the diaphragm.