A 1967 survey of the Minster revealed the central tower to be unsafe and close to collapse. Surveys showed the while some of the foundations had been built over the remains of the Roman fort of Eboricum, the rest lay on Yorkshire clay. The tower was slowly collapsing under its weight and twisting due to uneven subsidence. A massive £2 million pounds was raised to fund work to strengthen the foundations. This involved putting reinforced concrete jackets round them.
During this work, part of the Roman foundations were revealed as well as walls from the earlier Norman cathedral. When work finished, the undercroft was open to visitors to view these foundations.
Following the latest massive £20 million restoration project, a new exhibition has opened in the undercroft explaining the 2000 year old history of the site and exhibiting many artefacts found during the excavations.
Parts of the Roman foundations are displayed, along with the bases of Roman columns. There is the remains of a painted plaster mural which was rescued and reattached to the room where it was found. There are also Roman floor tiles.
The Norman remains include a sections of walls, and pillar bases. The course rubble walls of the Norman Minster were covered with a white plaster, which was painted with red lines to resemble mortar lines.
Display cases include artefacts found during the work. Roman remains include coins, glass and pottery fragments as well as broaches and pins.
The Anglo Saxon and Norman artefacts include a lot of carved stonework as well as floor tiles and statues. There are examples of medieval stained glass and books as well as vestments and rings.
There is a lot of written material and you do need to allow plenty of time to do the exhibition justice. It is worth visiting just to see the massive stone foundations of the church.
There are more pictures “here.”:http://wasleys.org.uk/eleanor/churches/england/yorkshire/north_yorkshire/york/york_1/minster/index.html