Mountjoy Castle is situated near the village of Mountjoy, in Magheralamfield townland in County Tyrone, Northern Ireland, on a hill overlooking Lough Neagh. It was built by Lord Mountjoy in 1602 and partly burned in 1643. It is a two-storey brick building and the lower storey is stone-faced on the outside. It consists of a central rectangular block with four spear-shaped angle towers with gun loops. The north west tower is partly demolished and the west curtain wall destroyed. The entrance was on the south side of the east curtain wall.