Also known as the Cathedral of St. Kentigern or St. Mungo's, Glasgow Cathedral dates to the 13th century. The edifice is mainland Scotland's only complete medieval cathedral - the most important ecclesiastical building of that era in the entire country. Unlike other cathedrals across Scotland, this one survived the Reformation practically intact, although 16th-century protestant zeal did purge it of all Roman Catholic relics (as well as destroying plenty of historical documents). Later, misguided architectural "restoration" led to the demolition of its western towers, forever altering the Cathedral's appearance.

The lower church is where Gothic design reigns, with an array of pointed arches and piers. The Laigh Kirk (lower church), whose vaulted crypt is said to be one of the finest in Europe, also holds St. Mungo's tomb. Mungo's death in 612 was recorded, but the annals of his life date only to the 12th century. Other highlights of the interior include the Blackadder aisle and the 15th-century nave with a stone screen (unique in Scotland) showing the seven deadly sins.

For one of the best views of the Cathedral (and the city, too, for that matter), cross the ravine (through which the Molendinar Burn once ran before being diverted underground) into the Central Necropolis. Built on a proud hill and dominated by a statue of John Knox, this graveyard (patterned in part on the famous Père Lachaise cemetery in Paris) was opened in the 1830s. It is emblematic of the mixing of ethnic groups in Glasgow, as the first person to be buried here was Jewish, as Jews were the first to receive permission to use part of the hill for burial grounds.