The best of Moyobamba [1] lies outside the city. In the town there is little to see besides the modern cathedral, on the Plaza de Armas and a municipal museum with sporadic hours on Benavides 380.
For a pleasant view of the Río Mayo, and the tiny river port of Puerto Tahuishco, head to Punta de Tahuishco, 20 minutes northeast of the Plaza de Armas (US$1 by mototaxi). The municipality has built a variety of gardens and pleasant overlooks in this neighborhood, known as Zaragoza. Nearby is Agroriente Viveros (Reyes Guerra 900, tel. 042/56-2539, agroriente [at] terra [dot] com [dot] pe), a commercial greenhouse featuring a wide range of local orchids.
Links:
[1] http://www.moon.com/destinations/peru/the-amazon/tarapoto-and-moyobamba/moyobamba