Ostróda County is dotted with traces of ancient and recent history. Old palaces and manors are a common sight. Many of them were brought back to their former splendour and now serve mostly tourism-related functions. These include: Anders Hotel, Karnity Castle Hotel, Manors in Bieniasze, Kraplewo or Sople, Palaces in Wojciechy, Klonowo or Pacółtowo. No less valuable are the numerous sites of religious architecture.
Most of the sites are in very good condition. Others are less impressive and often left unnoticed, hidden under a layer of earth. These are mainly former settlements, burial mounds and old cemeteries.
The largest and one of the oldest historic buildings is the fourteenth-century castle in Ostróda, built by the Teutonic Knights. It is a part of the Trail of Polish Gothic Castles.
Places especially worth visiting include: