The tower is protected by an invisible magical wall which extends underground and also keeps out weather.
The ward also creates an illusion that the towers are abandoned and about to collapse
Kolat Towers
A wizards' domicile that began as an old stone manor and a pair of sturdy cottages until its new owners—the wizard brothers Alcedor and Duhlark Kolat—bought the buildings in 1368 DR and stitched them together using transmutation magic, much to the chagrin of the city's building guilds. The guilds petitioned to have the building condemned but were ultimately unsuccessful, with the brothers' thrift and magical ingenuity being applauded by the locals instead.
The property is surrounded by a stone wall set with iron spikes. The taller tower is six stories, while the shorter is four and is accessible only via a bridge from the taller tower.
Both towers have fallen into disrepair over the decades. As neither of the Kolat brothers nor any potential inheritors have been seen in the intervening time, the brothers are widely assumed to be dead and their towers abandoned.