Hereford has been the seat of a Bishop since Saxon times, as far back as 680CE. The first cathedral dates from the 7th century though by Norman times was in ruins. The oldest part of the current cathedral, which is dedicated to St Mary the Virgin and St Ethelbert the King, date from the reconstruction begun by Robert of Lorraine who was made Bishop in 1079CE. The surviving parts of the church from this time include the Bishop's chapel and the nave arcade.
Further additions and reconstructions, as is common with most churches of any vintage, took place over the following centuries. The central tower was rebuilt in the 14th century. A Western tower added in the 15th. This tower collapsed in 1786 devastating the Western parts of the cathedral. The cathedral was restored in the mid-19th and early 20th centuries.
The cathedral of course is filled with historic artefacts (including the 13th century Mappa Mundi), tombs and monuments.