The doomed city - Arkadii Strugatskii

It is a mysterious city whose sun is
switched on in the morning and switched off at night, bordered by an
abyss on one side and an impossibly high wall on the other. Its
inhabitants are people who were plucked from twentieth-century history
at various times and places and left to govern themselves, advised by
Mentors whose purpose seems inscrutable. This is life in the Experiment.

Andrei Voronin, a young
astronomer plucked from Leningrad in the 1950s, is a die-hard believer
in the Experiment, even though his first job in the city is as a garbage
collector. As increasinbly nightmarish scenarios begin to affect
the city, he rises through the political hierarchy, with devastating
effect.