<Tr> <Th> Architectural style </Th> <Td> Modern </Td> </Tr> <Tr> <Th> NRHP reference #</Th> <Td> 12000515 </Td> </Tr> <Tr> <Th> Added to NRHP </Th> <Td> August 15, 2012 </Td> </Tr> <P> Built in 1959, the 45 - foot (14 m) concrete observation tower features a circular observation platform accessed by a spiral ramp . The ramp is 375 feet (114 m) in length, and rises at a 12 percent grade, in synch with the Clingmans Dome Trail . The platform, 28 feet (8.5 m) in diameter, allows spectators a 360 - degree panorama of the surrounding terrain . Cantilevered signs point out the various peaks, ridges, cities, and other features visible in the distance . Depending on the haze, visibility ranges from 20 miles (32 km) on hazy days to 100 miles (160 km) on very clear days . </P>

What 7 states can you see from clingmans dome