The vassal tower-stronghold of Angerja was probably built in the 14th century. The rectangular construction was made of limestone, the walls were two meters thick and it was surrounded by a moat. Some parts of the walls remain to this day and a moat is still visible. It is thought that the stronghold was destroyed during the Livonian war.
Tower-strongholds were built by vassals to protect themselves, mostly against peasant uprisings, especially after the failed St. George's Night uprising of Estonian peasants in 1343.
Easter Aquhorthies stone circle, located near Inverurie, is one of the best-preserved examples of a recumbent stone circle, and one of the few that still have their full complement of stones. It consists of a ring of nine stones, eight of which are grey granite and one red jasper. Two more grey granite stones flank a recumbent of red granite flecked with crystals and lines of quartz. The circle is particularly notable for its builders' use of polychromy in the stones, with the reddish ones situated on the SSW side and the grey ones opposite.
The placename Aquhorthies derives from a Scottish Gaelic word meaning 'field of prayer', and may indicate a 'long continuity of sanctity' between the Stone or Bronze Age circle builders and their much later Gaelic successors millennia later. The circle's surroundings were landscaped in the late 19th century, and it sits within a small fenced and walled enclosure. A stone dyke, known as a roundel, was built around the circle some time between 1847 and 1866–7.