Just one block away from the coast on one of the most desired residential beaches in South Carolina and sitting on over a half-acre lot lies one of the rarest and most unique real estate sales in all of Charleston. Part of the Harbor Defense of Charleston in World War II, the Battery 520 of the Marshall Military Reservation is a sub-post of Fort Moultrie built upon the ruins of the Revolutionary War and U.S. Civil War posts. At an elevation of 20' above sea level, this concrete coastal gun battery is located on the eastern end of Sullivan's Island, overlooking Breach Inlet, in Charleston Harbor. The residence is teeming with history. The Marshall Military Reservation was where the advance guard prepared for the Revolutionary War Battle of Sullivan's Island.Just down the street is Breach Inlet, home base for the H.L. Hunley, which in 1864 became the first submarine to sink an enemy ship in battle. Constructed in 1941 and following the attack on Pearl Harbor, the military combined its focus on sea coast defense with aerial defense. Existing batteries were camouflaged, but if detected, remained vulnerable to aerial attack. Therefore, the next and last generation of coastal artillery was mounted under thick concrete shields covered with vegetation to make them virtually invisible from above. This battery hosted two 12-foot long-range rifles mounted in casemate barbette carriages. It is considered among the largest batteries to be built. These 415,000-pound gun carriages shot 1 1/3 rounds per minute and were transferred from Fort Travis in Galveston, Texas. Designed for targets 15 miles offshore, these giant guns were only test-fired once (two shots), causing a tidal wave in the ocean, capsizing boats in the harbor, cracking plaster, and shaking chandeliers in Downtown Charleston. These guns were too large for this section of the East Coast and it was overlooked that Charleston lies on an earthquake fault line. Thus, for safety reasons, they were never fired again. The battery was deactivated in 1947 and the guns were returned to Galveston. The area now contains private homes. Since then, the bunker became a place of intrigue and a spot for parties. One story has it that one of America's Most Wanted Criminals, Trigger Burke, in 1948 hid out in the bunker with a stash of stolen money that was never recovered. The property was converted to residential use in 1972. The property has many one-of-a-kind features, such as incredible protection from hurricane-force winds and inclement weather. In addition, this concrete house does not experience termite damage. The home features 7,000 sq. ft., 4 large bedrooms, 3 full bathrooms, and 11 ft. ceilings. The structure supports 15-foot thick walls and steel reinforcement beams through the 150-foot long dwelling. There is an accommodating kitchen and dining area. A massive indoor hallway leads to 4 bedrooms and 3 full bathrooms. The front room is a large living quarters, marked by a bricked-in slightly sunken patio that once operated as a home soaking spa. This area is where the cannon was mounted and the 10 ft. hole is now filled in with sand to bring the beach to your doorstep. The residence has suffered no more than a broken window in Hurricane Hugo while most houses surrounding it were heavily damaged. A walkway leads to the roof highlighted by a metal rendering of a Wahoo Fish. This spot could likely support a more traditional one-story house without exceeding the town's height ordinance. It could then be connected to the bunker via an elevator and/or stairwell.