And since it was a rental you have to pay tax on the depreciation you took or could have taken on it.
See this FAQ for Rental Sale
https://ttlc.intuit.com/community/rental/help/i-sold-my-rental-property-how-do-i-report-that/00/2625...
See Publication 544 on Sale of Assets.
http://www.irs.gov/pub/irs-pdf/p544.pdf
