Initially the two villages were separate, but over the course of time, they grew and eventually merged.

De Molenwijk in Katwijk aan den Rijn, with many flats or apartments, was greatly changed in the 1980s.

A number of flats were also renovated, such as the flat on Tulpstraat (Tulip Street) with a number of shops at ground level including the well-known café, the Wachtje (little sentry or look-out).

Within the church is the tomb of Willem van Lyere en Maria van Reigersberch (1663), a principal work of Rombout Verhulst, and an organ (1765) in Rococo style.

The main road in Katwijk aan den Rijn is the Rijnstraat.