Sultan Abdul Mecit moved into the newly built Dol-mabahce Palace in 1853 , and by 1909 Topkape was completely abandoned.
Topkape now lies in ruins and that is why it was abandoned.  
mnli hypothesis: Topkape now lies in ruins and that is why it was abandoned.   premise: Sultan Abdul Mecit moved into the newly built Dol-mabahce Palace in 1853 , and by 1909 Topkape was completely abandoned.