Yep, ground leases are typically 50 years.
The dumbest ground lease arrangement I've seen in my career was the one for JFK Airport in New York City. The airport itself is owned by the Port Authority of NY & NJ but the land underneath it is owned by New York City. The city used to lease the land to the Port Authority for 20-25 years at a time. As the airport aged over the years, they were desperate to get investors to come in and construct new buildings to serve the passengers and cargo operators that use the airport. The air cargo buildings in particular were old and outdated.
Without a 50+ year lease none of the major industrial developers or hotel chains were willing to build anything there. Why spend a fortune building something on land you don't own and may only be able to use for 20 years? So you had obsolete (and vacant) air cargo buildings all around the airport property, and for years JFK was one of the only major airports in the U.S. without a hotel on the site. Meanwhile, you had cargo buildings and hotels built in the neighborhoods all around the airport where the location was far from ideal.
For all his flaws, Mayor Bloomberg put an end to that in the early 2000s when he signed the longest lease for the airport -- I believe out to 2050.