What is the largest town of Europe?

If we are calculating size by total population of the city, then London is the largest city in Europe, with a population of roughly 7.5 million.

hmm i think you will find London is a city

and the largest TOWN is in lancashire called Bolton and the reason why it is not a town is simply because there is a motorway down the side o the parish church.

so it cant be turned into a cathedral.......

I don't want to clog this answer up with an argument, but I think YOU will find that my answer is correct as the question implied a city. Why would anyone wish to know the largest town? You're using semantics here and I don't think that's justified. Plus, city status is not solely decided by the presence of a cathedral.