Buying liens against houses?

[Forrest Hull]

Hi everyone,

I am new to real estate but have put together of rough looking properties that are in nice areas. When searching one of these properties through my CAD, I found that one of the properties has property taxes due that go delinquent in December. The city tax collector website has the option to buy the city's lien against the house - does anyone have any experience doing this? I am really just trying to figure out what I am looking at here exactly. 

Thanks!

-Forrest