Is the most natural extension of the Space Lift. This idea is based on the fact, that looking from the Moon, Earth is a seleno-stationary satellite. On the Moon, there is a point, that has the Earth in the zenith all the time!
Therefrom, we should build a chimney, about 340,000 kilometers high, and wide enough to accommodate a cruiser ship. Modern carbon based materials are already strong enough for this purpose.
Then, we should build another chimney, much like the one on the Moon, only 8 or so times shorter, from any equatorial point on our planet. Just another model of the Space Lift.
Both chimneys are slightly curved at the top. The domestic one to the west, the lunar one to the east. Both ends meet once every day. There are thousands of kilometers of empty space between the tops at the the closest point.
They pass by each other with the speed of a ultra fast jet, relative to each other, several Earth radii high, somewhere above the Earth’s geostationary satellite area.
I would like those chimneys to be two transparent electromagnetic rail-guns. With some barely visible Faraday cage on the outside, for protection against the Sun’s weather.
Now, take this large cruise ship and eject it with this cannon, precisely enough that the Moon space chimney will catch it, decelerate it and lead it safely to the Luna.
The journey would take a few days in each direction, just as it took the last time we were on the Moon. Only the ship is much bigger now, transporting thousands.
This is what I mean by an Earth-Moon Tunnel. There should also be 24 space chimneys here on Earth, for a ship leaving port every hour. There could be several lunar chimneys as well. Maybe of varying height, to shorten the open space traveling time to a minimum. A minute in a three days voyage, perhaps.