Oast houses, with their conical roofs, were once as common a sight in Kent as windmills in Holland. They were also an integral part of the brewing process: the roofs are chimneys through which the smoke from the fires that dried the hops could escape.
However modern preparatory techniques have now taken over the traditional method of producing brewing hops. The only oast houses you are likely to see are those which have been converted into homes or museum pieces.