SHAFAQNA – The Grand Ayatollah Sistani answered a question about looking at non-Mahrams.
Question: What is the limit of looking at non-Mahram women without enjoyment?
The Grand Ayatollah Sistani: The issue of men looking at the body of non-Mahram women and also looking at their hair, with or without enjoyment, whether there is a fear of committing sin or not; it is Haram. And looking at their faces and hands to the wrist, if it is with lust or fear of committing sin, it is Haram. Rather the Mostahab precaution is that without lust or fear of committing sin, avoid looking.
And also it is Haram for women to look at the bodies of non-Mahram men with lust or fear of committing sin; rather according to Wajib precaution (even) without that (fear of committing sin or lust), must not look, except parts of the body which are not covered by men like head and hands and ankles which looking at them without lust or fear of committing sin has no problem.
And there is no problem looking at the bodies of fearless women who do not pay attention to anyone who instruct them to cover (Hijab), provided that it is without lust and fear of committing sin; and for this decree there is no difference between disbelieving (Koffar) women and other women, and also there is no difference between hands and face and other parts of the body which they usually do not cover.
Source: PERSIAN SHAFAQNA