Where does “London” come from?

London comes from Old English Lunden, from Latin Londinium, of unknown origin.

Ancestry of “London”, step by step

Step	Language	Word	Meaning
1	Middle English	London	—
2	Old English	Lunden	London
3	Latin	Londinium	London
4	Proto-Celtic	*Londinyom	—
5	Proto-Indo-European	lendʰ-	land, heath; loins

London — Etymology, Origin & Word History | Etymology Explorer