Towers are at Buddhist temples. While these are often called Pagodas
by Westerners, to the Japanese a Pagoda is an Indian style tower (see
below), not the Japanese style one with many roofs. When Buddha
died, it is said he was cremated and his ashes were split into eight
parts and sent to the eight provinces of India. Some of those ashes
later went to China, then part of those went to Korea, then part of
those went to Japan. Towers are erected only at Buddhist temples that
are supposed to have some of Buddha's ashes. There are over 1000
towers in Kyoto alone so Buddha was obviously extremely fat. Actually
some temples make claims about "authentic" ashes to distinguish
themselves.