As a part of my Old Dhaka(Puran Dhaka) expedition, I went at the Dhaka Christian Cemetery at Old Dhaka. I don't know exactly how old this cemetery is. But I've found several grave inside the cemetery which are around 200-300 years of old.
The exact location of the Cemetery is at Wari. This is just beside the "Salahuddin Specialized Hospital, Wari". Also its just one minute walking distance from "Baldha Garden". This place is not publicly available for visit. Only you have relatives are buried inside the cemetery, you are allowed to enter.
We don't have anyone there, so at first they didn't show any interest to enter the cemetery. But after our humbled request, and our interest about cemetery they have allowed us to enter the cemetery. If they guy didn't allow us to enter, we had nothing to do except leave the place.
I love cemetery. Every cemetery is a quiet place. When you'll enter the cemetery, you'll feel peace from your heart. Hundreds of our beloved people are buried here. I always try to read the notes that are written at grave. People wrote the words from their heart. Also you'll feel mournful when you'll find a grave where a son wrote about his mother(lets say at 1867), but later just beside the grave you'll find another grave where the son itself sleeping since his death. Its an exonerable fate, you can't avoid it. Everyone will die someday.
If you notice the Cemetery, you can easily distinguish two different types of architecture of the graves. One part is older one, the holy cross or the pillar beside the grave has baroque style, just like the Greek or roman style. These are older graves, around 200-300 years of old. Other part of the graves are newly build. Most of those are looks like our modern building structure. No fancy design or something like that. Only plain white painted.
So if you ever get a chance to visit the place, don't miss it.
Read about the old ruins of the Cemetery from the link http://icwow.blogspot.com/2010/04/dhaka-east-india-company-chiefs-tomb-at.html