If I paid off my commercial property in a different year from when I started renting and claiming it, do I report the interest as part of the cost or do I report it in the interest line?

I bought a commercial property in 2006.  It's paid off.  Never claimed the interest, improvements, or anything on it.  I started renting it on 2021.

When I enter the property cost, do I include everything I paid for it including the interest?  Do I enter the interest separately?  Or can I even claim it at all?  Thanks for any help!