Soviet scientists of the 60s believed that the moon was an artificial object

In 1969, Moscow scientists M. Vasin and A. Shcherbakov published
a work (https://bit.ly/31ucf1D) "The Moon is the Creation of
Reason", in which the hypothesis was put forward that our "natural
satellite" is an artificial celestial body having two protective
shells.
1) Heat and meteorological layer, about four kilometers thick;
2) An armored protective layer, approximately fifteen kilometers
thick, under which there is a huge habitable cavity.
The researchers proceeded from the fact that lunar craters and
"circuses", which, according to world science, are of meteorite
origin, despite the colossal spread in diameters, have almost the
same depth, up to three kilometers. This could only take place
when the meteorites, bumping into the armor protective layer,
scattered the material and meteor-protective shell of the moon's
surface, since all the energy released during the collision met
an insurmountable obstacle on its way. This is what caused
the formation of the lunar ring mountains "circuses", from the
center of which the ridges of the mountains are not always
visible, since the latter are located beyond the lunar horizon.
The hypothesis of M. Vasin and A. Shcherbakov was
experimentally confirmed in 1969, when, in the process of
exploration of the Moon under the Apollo program, gravitational
and magnetic anomalies were discovered (https://bit.ly/31FIw5K),
indicating the presence of metallic masses, hidden under the lunar
surface "mascons" and "micromascons". During seismic sounding
of the Moon by dropping the take-off stages of the Apollo lunar
landing modules onto its surface, "reverberation" was discovered,
that is, the residual sound of the Moon, lasting up to two hours.
Seismometers installed by the Apollo astronauts in the area of
Bulliald crater (southeastern part of the visible disk of the Moon)
systematically transmit signals to the Earth
(https://bit.ly/3puoPGa), which, in contrast to rare sporadic
moonquakes, have a monotonic rhythm. According to some reports,
there are five huge objects ranging from 8 to 22 kilometers under
the lunar surface. Some of them have been identified in the infrared
range by the European research satellite "Cosmic lab"
(https://cnn.it/3EtCOT1).
To what has been said, it should be added that the spherical shape
of the Moon is the most optimal for artificial space objects, since
it allows isolating the maximum volume with a surface with a
minimum area. Of course, a long, over millennia, meteorite
bombardment has done its job, and tens of thousands of large and
small craters visible today only indicate that the Moon is a very
old object.