Gillette Castle State Park

Gillette Castle State Park is straddling the towns of East Haddam and Lyme, Connecticut, in the United States. Sitting high above the Connecticut River, the castle was originally a private residence commissioned and designed by William Gillette, an American actor who is most famous for his portrayal of Sherlock Holmes on stage.

Gillette's estate, called Seventh Sister, was built in 1914 on a 184-acre (74 ha) tract on top of the southernmost of a chain of hills known as the Seven Sisters. After Gillette died, with no wife or children, his will precluded the possession of his castle by any "blithering sap-head who has no conception of where he is or with what surrounded". Connecticut's government took over the property in 1943, renaming the home as Gillette's Castle and the estate as Gillette Castle State Park. The estate was added to the National Register of Historic Places in 1986.

Located at 67 River Road in East Haddam, the park consists of the castle and its grounds and receives 300,000 annual visitors. It reopened in 2002 after four years of restoration, costing 11 million dollars. It now includes a museum, hiking trails, and a picnic area, and holds many theatrical celebrations.

There are a number of oddities in the castle personally designed by Gillette, such as unusual doorknobs and locks, and a system of hidden mirrors for surveillance of the public rooms from the master bedroom.

The grounds used to have a railroad track with a working steam engine and electric engine that visitors could ride on, also designed by Gillette. Some of the track was purchased by Lake Compounce in Bristol, Connecticut and is in use to transport guests around the lake. The remaining track was pulled up and converted into walking trails. From the castle's garden one can see the Connecticut River. The engines were donated back to the park in 1992, where the electric engine is on display and the steam engine awaits restoration.