Vestby is a municipality in Akershus county, Norway. It is part of the Follo traditional region. The administrative centre of the municipality is the …Vestby is a municipality in Akershus county, Norway. It is part of the Follo traditional region. The administrative centre of the municipality is the village of Vestby. The municipality is named after the old Vestby farm, since the first church was built here. The first element is vestr which means "west" and the last element is býr meaning "farm". The neighbouring farms have the names Østby, Sunnby, and Nordby ; and they must all four be the parts of a bigger and older farm, whose name is now unknown.