It was supposed to be A . But nowadays it is B which holds that title .
What ?
Clue : Indian region

A

B
Quoting Appu ,
“A – Palace of Culture in Warsaw
B – Triumph-Palace apartment building in Moscow, sometimes called the Eighth Tower or Eighth Sister because it is similar in appearance to the Seven Sisters skyscrapers built by Stalin in Moscow”
Cracked by Appu , Nishanth Raman and Arun .
A – Palace of Culture in Warsaw
B – Triumph-Palace apartment building in Moscow, sometimes called the Eighth Tower or Eighth Sister because it is similar in appearance to the Seven Sisters skyscrapers built by Stalin in Moscow
The Indian connection must be your ‘region of expertise’, going by Shiroi Lily: Seven Sister states in the North East.
Seven Sisters of Moscow?
Warsaw’s palace of culture and science (stalin’s syringe) replaced by Moscow’s ‘triumph-palace’(stalin’s eighth sister) as the europe’s tallest buildings.