I operate an observation hive in a commercial building, a nursery in a 
family farm/market.  The hive sits 3' off the ground, with a small 2' long 
horizontal exit.  This intersects a vertical tube which is a 6" x 6" square 
acrylic tube, 10' high as measured from the hives standard 2' horizontal 
exit.  The top of the tube then goes through a wall horizontally, with an 
overhang to help protect the tube from rain.  With the hive base 3' off the 
ground, the entrance/exit is 12' high.  This setup allows the visitors to 
see the bees coming and going, and keeps them as protected as can be.  In 
all the years I have operated it, no visitor has been stung by a honeybee, 
despite the tremendous number of visitors to the farm to shop and take the 
rides in the amusement park.

Several problems encountered were the temerature/pressure difference from 
inside and out, resulting in a draft that must be kept out of the hive.  
Keeping the tube from going directly into the hive was the answer.  The 
vertical tube is longer than necessary to go from the roof to the hive, 
with a removable screen at the bottom, several inches below the horizontal 
exit of the observation hive which intersects it.  This allows dead bees to 
be removed, as the bees will drag them out of the hive to the screen, and 
any that die near the entrance, will naturally fall to it as well.  Once 
the bees are accustomed to the tube, the screen can often be removed, 
cleaned and replaced without any bees exiting into the room.  Rainfall is 
another problem, but a small roof or shedding structure at the top will 
help.  Security may be another problem, if the solution to your situation 
allows inadvertent access through an opening that would allow someone the 
ability to open it further and gain access from the outside.  One way to 
overcome this is to set the hive/vertical tube near a wall with a gable end 
of the building.  This usually allows a peak ceiling, small shed roof on 
the exterior, and horizontal exit that can eliminate dealing with later 
leaking problems.

The bees do try to walk up, with difficulty, as well as fly.  The overall 
setup does add stress, but then any observation hive is always under added 
stress relative to a standard hive.  If you maintain the hive well, as any 
observation hive needs to be, the extra length for the exit shouldn't be a 
problem.  It does take a while for them to figure out how to get in and 
out, but they do figure it out.  The trick of adding a string is a good 
one, and works well, with or without sugar syrup on it.  I did encounter 
one situation in which the bees attempted to build additional comb at the 
base of the vertical acrylic tube during an exceptionally heavy nectar 
flow.  

Good luck with your hive.

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