Colosseum was built in 80AD in Rome. It's height is 48m,0.048km, and 4800cm. Colosseum was built to host Gladiators contests and pubic spectacles Suck mock sea battle. Romans used captured slaves to building the colosseum.
63uilding was build in Korea in the time when it was 1980~1985 63 Building was 249m,0.249km, and 24900cm. It was build as a landmark for the 1988 Olympics.
Eiffel Tower was build in France in 1889. It's height is 324m, 0.324km, and 32400cm Eiffel Tower was built for the worlds exhibition that was held to celebrate France revelation in 1889.