Caroline Furnace Lutheran Camp and Retreat Center is located on the site of an old iron ore smelting furnace, it began producing iron in 1835 and was named Caroline Furnace. It was owned by Benjamin Blackford and was named for one of his three daughters. He also owned two other furnaces in the area that were named for his other two daughters, Elizabeth and Isabella.

The iron ore (also called pig iron) was transported down the mountain toward Luray by ox cart and shipped on barges from Bixler's Ferry (then known as Caroline Furnace Ferry) down the south fork of the Shenandoah River to Harpers Ferry and beyond. After the the iron was sold, the barges were taken apart and sold for lumber and the barger then walked back up river to build another barge and deliver more iron.

Caroline Furnace operated during the warmer months with about 20 men actually working at the furnace and an additional 100 men mining ore, cutting wood and making charcoal. The Master of the Furnace was in charge of the operation and it was his job to judge when the iron was ready to pour. When it was ready, he would draw a line in the sand with several off shoots, knock out the plug and let the iron drain into the indentations in the sand. It resembled a mother pig with her piglets suckling and that's where the name pig iron came from.

Each day the furnace consumed 600 to 800 bushels of charcoal and tons of ore and limestone in producing about three tons of pig iron each day.