From round cities to space rings

unpleasant. In any case it is not entirely clear which method is
best.
Electromagnets or permanent magnetic plates would be placed on
the floor, but slightly below to reduce its intensity, permanent
would be mainly in the areas usual walk and electromagnets in
areas such as housing where it is not necessary to operate
continuously. The biggest flaw of this system is that only gravity
acting on magnetism sensitive materials and not on all.
Another advantage of living on the surface of planets would be
that there would not exist the risk of losing the reaction gases
from the ships, to be caught by planetary gravity thus could be
used indefinitely. On planets and moons with low gravity and no
atmosphere, the loss of these gases would avoid building a
network of communication tubes and domes for cities connected
to each other remain connected around the globe and completely
sealed habitable zones.