I just traveled to Nanjing couple days ago. Too bad, i don’t have a chance to try the MRT (Metro) there. Actually i have seen the Metro signboard when i walk around Nanjing that time, but when i follow the sign, i could find the Metro Station. Nanjing Metro (MRT) has just opened in 2005. It’s quite new compared to Beijing Subway and Tianjin Metro. But the line has been built is only 2 line (similar to Tianjin Metro). So we couldn’t only depend to this Metro to go every place in Nanjing. The fare for Nanjing metro is varies and it’s distance-based. Minimum fares is 2 yuan (USD $0.30) for one journey.
And for long term, Nanjing Metro (MRT) System Map will be like this