Apple’s futuristic spaceship campus in Cupertino has been valued at over $4 billion, according to the Santa Clara County assessor. This valuation comes as Apple has pushed back against property valuations in the past in an effort to avoid property tax.

According to the assessor, Apple Park itself is worth $3.6 billion. Once you factor in things like computers, furniture, and grounds maintenance equipment, however, that valuation increase to $4.17 billion. David Ginsborg, deputy assessor for Santa Clara county, said coming to a valuation for Apple Park was challenging because everything is custom-made:

This valuation makes Apple one of the world’s most expensive buildings, alongside the likes of the One World Trade Center, the $15 billion Abraj Al Bait Towers, and $100 billion Great Mosque of Mecca in Saudi Arabia, and more (via SF Chronicle).

Apple is required to pay 1 percent property tax per year, which comes out to just over $40 million this year. Some people, however, believe that Apple should pay more, as its property tax does not “offset its contribution to the housing crisis and homelessness.” Nonetheless, Apple is still the largest property taxpayer in Santa Clara County.

Of the over $40 million Apple will pay in property tax, 25 percent goes to funding the local elementary school, while 15 percent goes to the fire department. Cupertino itself receives 5 percent for discretionary spending.

When it originally came to an agreement with Cupertino to build Apple Park, Apple paid $5.85 million into an affordable housing fund and invested $75 million to improve city infrastructure and traffic. Apple has regularly appealed property tax rulings in Santa Clara County, and is the county’s leading appealer of such assessments.