The Tower was Ravians first retreat, the haven to practice in the years he was still learning the crafts of the magi.
While later the building took another role. After the conquest of Marianon - the 3rd Citadel - and his subsequent rise to his position in the courts of Arganon; Ravian weaved an array of magics around the whole tower. This he did to the knowledge of no other. The tower was safer in its unassuming guise, holding chambers of secrets and treasures in a sprawl far under its cellars. To the casual wanderer and often ill-fated squatter it appeared abandoned, and as if it had done so for many a year.
The tower has two entrances. One for the mage lord and one for the current "occupants". Part of the spellcraft was to beleaguer anyone entering into taking the staircase intended for them. It would always appear the spiral led to the common entrance.
To this day the secrets of the vaults have remained.