Bhaktapur is one of the ancient cities of Nepal. The other two were Kathmandu and Patan (also known as Lalitpur). The Bhaktapur durbar Square has some very beautiful temples and architecture. Bhaktapur is only 12 km from Nagarkot and you can explore this region while staying at Nagarkot. Local buses are available from Nagarkot to Bhaktapur. But be prepared for a bumpy ride. The local buses are also usually very crowded. You can also hire a car for Bhaktapur and rest of Kathmandu sightseeing.