Sources for: Biggest Cities of Charlemagne’s Empire in 814 A.D.

(1) - https://ssh.datastations.nl/dataset.xhtml?persistentId=doi:10.17026/dans-xzy-u62q
For most city populations.

(2) - https://ssh.datastations.nl/dataset.xhtml?persistentId=doi:10.17026/dans-xzy-u62q
For Quentovic (35 hectares, ~100/ha) and Dorestad (45 hectares, ~100/ha).

(3) - https://www.academia.edu/49032934/Bardowick_Ein_siedlungsgeschichtlicher_Abri%C3%9F_aufgrund_des_neuesten_Forschungsstandes
For Bardowick (~60 hectares in the late 8th century, ~100/ha).

(4) - https://studenttheses.uu.nl/bitstream/handle/20.500.12932/40598/Common%20Land%20in%20the%20Carolingian%20Central%20Netherlands%20Master%20thesis%20Lucas%20Helder%20(Scriptiearchief).pdf?sequence=1
For Deventer (~28 hectares, ~100/ha).