Llandough lies to the northwest of Penarth overlooking the capital city of Cardiff, Penarth and the Bristol Channel. Llandough Hospital is one of the largest hospitals in the Cardiff area. Excavations have shown that the village's history goes back as far as the Roman occupation of Wales. The site of a Roman villa was found during excavations of a neighbouring farm in the 90's.
Llandough was long believed to be one of the main ecclesiastical centres in south east Wales, and was almost certainly the site of St. Dochdwy's monastery. Evidence to support this claim was found when the excavations of the Roman villa revealed post-Roman burials, and also during another excavation in 1994, when the remains of over 800 individual burials, all dating from the 4th century to the 12th century AD were revealed.
However, this monastery no longer exists. It was perhaps overshadowed by the ecclesiastical site at Llandaff, and reduced to the importance of a parish church. The current church, which was built in the middle of the 19th century by the Llandaff diocesan architects, Prichard and Seddon, replaced one built a few years earlier, which was apparently sold to the next village of Leckwith, and moved piece-by-piece to be erected there. A 10th- or 11th-century stone cross, with the incised name Irbic, stands in the churchyard at Llandough.
To the west of the church, are three fragmentary components of a well-fortified house dating from the 1420s or 1430s believed to have been built by John de Van.
Until the mid-1960s, Llandough was a small farming and quarrying village but experienced an expansion involving the building of a large number of houses, a primary school and a block of six shopping units. However, these shops have now been demolished.