Llangynog (grid reference SJ053261) lies at the confluence of the Afon Eirth and the Afon Tanat at the foot of the Berwyn range in Powys, Wales.
It lies at the foot of the Milltir Cerrig mountain pass on the B4391 road, which runs between Llan Ffestiniog and Llanfyllin (though the B4391 road number 'disappears' between the western end of Llyn Celyn and Bala).
It is surrounded by mountains and is a popular base for walkers. Llangynog has a down-hill mountain bike course, and a crown green bowling club, who play in the Oswestry League.
It was the western terminus of the Tanat Valley Light Railway (Llynclys - Llangynog) (15 miles); it opened on 5 January 1904 and closed (passenger traffic) in 1951.
It is close to the pilgrimage shrine of Saint Melangell at the church of Pennant Melangell (grid reference SJ024265). Lake Vyrnwy is a short drive away. Bala Lake, Powys Castle in Welshpool and Oswestry take around half an hour by car. Wrexham, Chester, New Town and Shrewsbury are all under an hour away. The seaside town of Barmouth is also within easy reach by car.