Consider this about Constantinople: 1. It was surrounded on three sides by water. 2. It was located at the crossroads of Europe...

Consider this about Constantinople:

1. It was surrounded on three sides by water.

2. It was located at the crossroads of Europe and Asia. 

3. It's harbor could easily be guarded against attack.

4. It was 800 miles east of Rome.

How can you best characterize thsee features of Constantinople?