The museum is located in the Courthouse on Market Square. This interesting building was built in about 1600, with additions in 1706 which included the frontage with the loggia on the ground floor. Offices and a jury room were provided on the first floor, and part of the original building was converted into a most interesting panelled courtroom. It was in this building that the Kinsale Town Corporation and its sovereign conducted their affairs and the Courthouse was also used for ceremonial occasions in the 18th century.

The Museum in the Courthouse has many interesting items on display which includes a display on the famous Kinsale Giant. He was Patrick Cotter O'Brien. He died in 1806 and is believed to have been over 8 foot tall. The Museum also houses the largest collection of maritime artefacts in Ireland.