Bhaktapur, a medieval city dating to the 9th Century, is one of the seven original communities that eventually became Kathmandu. Patan is even older (3rd Century) but now is faster-paced and more cosmopolitan. As in old Kathmandu, life centers around the ‘Durbar’, or Palace Square.
But what a contrast! Kathmandu hustles and bustles. The constant ebb-and-flow of tourist flocks makes photography difficult. The Durbar at Bhaktapur (or, by its modern name, Bhadgaon) is a tranquil place to meander, contemplate, and compose photos at leisure. Shops along the narrow, yet inviting, cobblestone streets adjoining the square have higher-quality merchandise.
Highlights: Locals gathering at the Lion Gate to the main temple. The interior courtyards. The pottery square, with artisans at work. The relaxed, low-key street markets.
The square at Patan, also filled with a variety of temples and monuments, is similar --- yet different enough that you should see both. Walk 10 minutes to the public baths and Temple of Kumbeswar for the colorful sight of women doing their laundry as gaily-dressed children play nearby.
With a guide and driver, and not returning to your hotel for lunch, you can see both cities in four hours or so.