The archaeological site of Novae is situated in northern Bulgaria, on the Danube. The ruins are located 4 km to the east from the town of Svishtov, on the road to Rousse. If you travel to Bulgaria, you may choose either Sofia or Rousse as a point on the way to Novae. Another solution is to fly to Bucharest, and than either to Rousse, or to Zimnicea. Svishtov may be reached by bus from Rousse (about 80 km) or from Sofia (240 km). If you travel through Romania, you can cross the Danube on the ferryboat in Svishtov. You can check the connections here:
If you travel by plane, the best connections are from Sofia and Bucharest. The buses from Sofia go every day, and the journey to Svishtov takes ca. 3-4 hours. When travelling from Bucharest, you may try to go by train to Rousse, and than by bus to Svishtov. Another option is to take the bus from Bucharest to Zimnicea, and then across the Danube to Svishtov.
Travelling by train is more complicated, but cheaper. You may check the connections here:
By car, it is better to travel through Romania, along the Danube and to cross the river in Svishtov. When you pass the Zimnicea and take the direction southwards, you may see the site from the Romanian bank: