https://www.vice.com/en_us/article/wx874b/how-spacexs-plan-to-convert-oil-rigs-into-launch-pads-could-work

SpaceX has acquired two decommissioned offshore oil rigs at ports in Texas, which the company plans to convert into spaceports to service its Starship launch system, a project that is still under development. 

The rigs were purchased from the offshore drilling contractor Valaris for $3.5 million apiece in August 2020, through a company called Lone Star Mineral Development LLC, according to CNBC. The company is registered to SpaceX CFO Bret Johnsen; shortly after it was incorporated in June 2020, SpaceX announced that it was seeking “a team of engineers and technicians to design and build an operational offshore rocket launch facility."