Alcatraz Island is situated in San Fransisco Bay and is famous for the high security jail constructed here. This jail was in operation from 1933 to 1963 and it kept captive most of the dangerous criminals of that time.In 1972 this island was converted into an entertainment zone .Ever since guests, security people and other personnel have complained of ghostly activities here.
People have even complained of hearing crying and beating of the gates.Ghost sighting was even reported when this jail was active. One night a prisoner was screaming that a green monster was trying to kill him .The next day that man was found dead with strangulation marks on neck. After this episode at counting there would always be one extra person reported.
Image Source: https://en.wikipedia.org/wiki/Alcatraz_Island