Elon Musk’s The Boring Company has finished construction of its test tunnel under Los Angeles.

The tunnel has been built to test the viability of Musk’s underground transport concept and has been just over 12 months in the making. According to The Boring Company’s chief executive, the tunnel will be opened to the public on December 10 and people will be offered free rides.

Taking to Twitter, Musk said that he recently walked the full length of the tunnel, describing it as “disturbingly long.” It measures two miles (3.2 km) in length.

While the concept has yet to be proven, Musk was given the go-ahead to dig up a small piece of land in the District of Columbia in Washington D.C. earlier this year to build a Hyperloop. At the time of the announcement, The Boring Company said that it was still acquiring the correct permit to dig under city roads and other public places.

Things don’t stop there.

In June, The Boring Company was awarded a contract to build a Loop system between Chicago O’Hare Airport and downtown. Unlike the Hyperloop, Musk’s Loop system doesn’t ferry passenger at speeds of over 700 mph (1126 km/h) in vacuum tubes but is instead made up of 16-passenger sleds that travel in tunnels at roughly 100 mph (160 km/h).

It remains to be seen how much the system will cost to construct but Musk’s company will foot the bill, estimated to be around $1 billion. Under the proposed Loop, passengers will be able to travel from downtown to Chicago O’Hare in 12 minutes and for between $20 and $25.