The English historian, John Capgrave, wrote that St Cyngar established a monastery in Glamorganshire with 12 canons dedicated to the Holy Trinity. It is believed this was the beginning of Holy Trinity Church. In 1874, the remains of what appeared to be a monastery were still visible. The parish consisted of Marcross Manor, owned by Sir Philip de Marcross from 1189 to 1200. De Marcross' only heir was a daughter; when she married in about 1250, the manor passed to William le Butler. The church was described as a rectory worth five marks in 1254, and was still described as such in 1535. By 1563, it was noted as having a parson and curate; by 1835, while it remained classified as a rectory, the listing for patron was the Chapter of Llandaff.
The main structure dates from the 12th century; it is believed that the tower was added to the building in the 14th century. The tower, with its saddleback roof, may have been partially rebuilt in the 17th century, from evidence of a difference in masonry above its ridge. The rounded Norman arch at the church entrance dates from circa 1150 and the large font with rolled mouldings dates from the 12th century. There are no aisles in either the chancel or nave. One of the chancel walls has two trefoil light windows believed to be from the 13th century. One of these windows may have been used for the ringing of a Sanctus Bell. The building is constructed of stone with slate roofing, with the roof for the chancel being lower than the nave. Still in the chancel is the lepers' window, where those with contagious diseases could view church services without coming into contact with others.
By the late 19th century, it became evident that the church was in need of restoration work. The rector of Holy Trinity began a fundraising campaign for the work; it took four years to raise the needed funds. By 1892, enough donations were received to allow Kempton and Fowler of Llandaff to begin the project. During the restoration, the architects discovered many items of note which had been hidden by previous renovations to the church. While removing old plaster from the walls, a doorway leading to the rood loft on the north side of the chancel arch was uncovered. The plaster removal also located a 13th-century tomb in a recess of the north nave wall. During the restoration, a tomb in the chancel floor from circa 1200 and the church's original pillar piscina were also located.
When the restoration was completed, the church had been completely re-roofed, the church walls and tower were renovated, new floors were installed along with new pews, a new pulpit and reading desk, as well as a new altar and altar rail. Holy Trinity was reopened in 1897.
The Amphitheatre of the Three Gauls was part of the federal sanctuary of the three Gauls dedicated to the cult of Rome and Augustus celebrated by the 60 Gallic tribes when they gathered at Lugdunum (Lyon). The amphitheatre was built at the foot of the La Croix-Rousse hill at what was then the confluence of the Rhône and Saône.
Excavations have revealed a basement of three elliptical walls linked by cross-walls and a channel surrounding the oval central arena. The arena was slightly sloped, with the building"s south part supported by a now-vanished vault. The arena"s dimensions are 67,6m by 42m. This phase of the amphitheatre housed games which accompanied the imperial cult, with its low capacity (1,800 seats) being enough for delegations from the 60 Gallic tribes.
The amphitheatre was expanded at the start of the 2nd century. Two galleries were added around the old amphitheatre, raising its width from 25 metres to 105 metres and its capacity to about 20,000 seats. In so doing it made it a building open to the whole population of Lugdunum and its environs.