Beginning of the Bosphorus starts with Rumeli & Anadolu Light Houses in the North & ends with Ahirkapi & Kadikoy Incirburnu lighthouses in the south. Considering it is the border of Europe and Asia , Bosphorus gives its uniqueness to Istanbul City.
One of the reason that Istanbul called dream city is basically comes from this natural strait, as this is the only city that you can wake up in the Asia and can go to work in Europe at the same day. It sounds magical but it is the truth that majority of the Istanbul population lives in the Asian Part of the City and due general business districts located at Europe side, this unique dream comes true everyday.