Manufacturing St Catherine is second only to Kingston as an industrial center. Industrial plants are some of the biggest employers in the parish. Spanish Town has the largest salt producing plant in the Caribbean, while Jamaica Milk Products, an affiliate of the Nestlé organization, has a factory in Bog Walk, another major town in the parish. The largest power plant in the island and several factories are located in Old Harbour. Twickenham Park, near Spanish Town, is another industrial estate with mainly light industries including cigarettes, carpets, batteries, plastic items, medical and pharmaceutical products. Tourist sites Jamaica's emancipation Square can be found in Spanish Town. This is the only Georgian square in Jamaica. Kings House and the House of Assembly on the west and east sides, respectively, were erected in 1762. The Courthouse was built in 1819 and used as a chapel and armory with the Town Hall upstairs. The Rio Cobre River and Gorge is one of the largest in the island. Sinking at a place called River Sink at Worthy Park, it runs underground for nearly six kilometres, then surfaces at River Head Grand Cave in St Thomas-in-the-Vale. Before entering the gorge it is joined by a number of tributaries, such as the Thomas River, the Rio D'Oro and the Rio Pedro. In the early 1770s, a road was opened through the gorge. The Flat Bridge was originally constructed of logs, which were washed away in a flood. The present bridge was built and it has withstood countless floods. A marker can be found, which shows where the water rose to over above the bridge in 1933. An apocryphal story is that at noon, on every Good Friday, for a short period of time the ghosts of all the slaves who drowned in the river can be seen. Caymanas Race Track, Jamaica's most famous race track, is in St Catherine. St Clair Cave, one of Jamaica's more famous caves, is found in the parish. This large, complex cave contains one of the most notable bat roosts on the island, and is one of the few known historical sites for the possibly extinct bat, Phyllonycteris aphylla. Because of the biological importance of the system, and the inherent dangers involved in exploring it (i.e. noxious gases, histoplasmosis, Cutaneous larva migrans, difficult footing), casual visitation is discouraged. Government and infrastructure The Rio Cobre Correctional Centre of the Department of Correctional Services,