This was the residence of the former bishops of Laon in medieval times, and has been the town's courthouse since 1811.
Due to the nature of the building, you won't be able to get inside these days - although you should know that its two remarkable chapels can usually be visited during the Heritage Days - but take a look at the beautiful sundial that adorns one wall of the inner courtyard, and as you turn around, meditate on the gargoyles of the seven deadly sins that spring from the adjoining cathedral!