Constantinople lay on the European side of strait called the Bosporus.
Bosporus strait.
No. It's located on what is either called "the Bosporus" or "the Istanbul Strait". It is both the same thing, Istanbul Strait being a name less used. The city located there was of course called Constantinople only until 1453. Since then it has been called Istanbul.
The name is bosporus
Bosporus strait
The Bosporus Strait, the Black Sea, and the Sea of Marmara surround Constantinople or Istanbul.
Through the Bosporus Straits and the Sea of Mamara
It's better to ask one question at a time, rather than to cram two questions into one. The city is Istanbul, aka Constantinople in older times. It has a section in Europe, and a section across the Bosporus in Asia.
Constantinople was originally called Byzantium, which is where the name for the Eastern Roman Empire after the Western half fell came from (The Byzantine Empire). It became Constantinople when Constantine converted it to Christianity and improved it. Located on the Bosporus Strait, it was very well placed strategically, with water on three sides and right on many major trade routes.
Istanbul (Constantinople) links Europe and Asia. The city is situated on both sides of the Bosporus Strait, meaning it is situated in both Europe and Asia; it is like a bridge that connects the two continent.
The location of Constantinople (now called Istanbul) at the Straits of the Bosporus and Dardanelles (the narrow passage between the Aegean Sea near Greece, and the Black Sea) has been a route for invading armies from both the north and the south.
It was able to control key trade routes between Europe and Asia.
Constantinople was a city, therefore it only had one location. Constantinople was on the Bosporus, the strait which separates Europe and Asia and connects the Mediterranean Sea and the Black Sea, in northwestern Turkey. It is now the Turkish city of Istanbul.