The Great Lakes Mage Tower claims to be the original mage tower. I have not played the game long enough to know if this is true, but certainly have not reason to doubt it. I was easily able to find the tower since it is so close to the Moonglow Moongate and to the Western Road.

There were several mages/warriors there using the building, but no staff members. I was told that staff are generally there a little later in the day. The tower itself is well decorated including an extensive lab on the second floor.

Several visits to the tower and I have always found someone present. Most times I do find someone with "Mage Tower" over their head. There is usually a deamon, elemental, or chicken somewhere as well. Often the chickens talk :)