Mynydd y Lan is a 381-metre-high flat-topped hill in Caerphilly county borough in South Wales. It falls largely within the community of Ynysddu but its northern and eastern margins are within Crosskeys community. Its largely wooded southern and eastern flanks rise steeply from the Sirhowy and Ebbw valleys respectively. A wireless transmission station is located towards the northern end of the summit plateau. The current name is a possible corruption of Mynydd y Llan (mountain of the church), referencing the parish church of St Tudor, situated on its plateau. the church site has been occupied since the 5th century, with an early British site, being replaced by the Norman 11th century church.