Church of St. Tysilio has 12th century roots, but has been thoroughly rebuilt in the fifteenth century. In the early period of its existence, it was certainly owned by the nearby Valle Crucis Abbey. In 1718, the northern transept was added to the church, and in 1869 a Victorian restoration of the building was carried out.
The church was erected from rough stone and from sandstone blocks in the corners. The nave and the chancel of the church form one entirety, covered with a gable roof. From the south, the main entrance to the nave is located in the porch, and from the north to the chancel, an early modern transept was added. The oldest window from the 13th / 14th century has been preserved in the corner of the nave and transept. It is narrow, rounded at the top and framed with carved patterns. A large gothic window with a tracery in the eastern wall dates from the fifteenth century, while the window now hidden in a transept, from the 14th century. Inside the church there is a medieval roof truss, a 15th-century rood screen separating the nave from the presbytery, topped with an oak eagle and an eight-sided baptismal font from the 15th century.
Website britishlistedbuildings.co.uk, Church of St Tysilio A Grade II Listed Building in Llantysilio, Denbighshire.