Corrections in red; stylistics in blue.

I LOVE YOU, ISTANBUL!

Every soul needs to plunge into a vortex of unforgettable emotions at least once one's life.  [1]
That moment when you don't sense anything around you, other than the great pleasure of something. You even do not realise what this feeling is...  [2]
Only splendour meets every of your step ... no drawbacks....
That is how I feel myself in my lovely city.  [3] 
I LOVE YOU, ISTANBUL!

[1]  Variants:  ... at least once in his life.    ... at least once in his or her life.  ... at least once in their life.

[2]  More common variant:  You do not even realise what this feeling is...

[3]  When translating "чувствовать себя" into English, do not translate "себя".   Examples:  I feel wonderful.   She feels sad.   We feel sick.