One of the earliest accounts of the Holy Year dates back to a Spanish historian, traveler and pilgrim called Pedro Tafur in 1437. Tafur connects the Jubilee indulgence with the right of sanctuary for those who had escaped persecution. He also noted its existence in pagan times for all who crossed the threshold of the "Puerta Tarpea" previously upon the site of the Archbasilica of St. John Lateran. Accordingly, at the request of Emperor Constantine I, Pope Sylvester I published a Papal Bull proclaiming the same immunity from punishment for Christian sinners who took sanctuary there. The privilege, however, was quickly abused and at some point was even commercialised resulting in popes consequently ordering the door to be sealed with a wall, only to be unsealed during Jubilee years. The wall was destroyed and the door opened once in a hundred years. This was later reduced to fifty years and now "opened at the will of the Pope".