Wow, this is awesome! I rent an apt in a brownstone. The brownstone up the street sold recently for $3.4MM. The documents you linked show the annual taxes at $8,700 = 12.5% * $67,000 (Billable assessed value). The document says the estimated value is just under $1,000,000.

$8,000/year doesn't seem outrageous for a $1mm property with rental income, especially given that it's estimated value is about 2/3rds under what it should be.