Ahrensburg is a town in Schleswig-Holstein, Germany and it is a part of the Hamburg Metropolitan Region, which is situated in Stormarn.

Its outstanding sight is the Renaissance castle dating from 1595.

Other sights are the adjacent castle church with its "Gottesbuden" Almshouses.

Ahrensburg is situated in the Tunneltal, in which Alfred Rust excavated many items dating back to the ice age.