To unlock the art galleries you have to get a certain amount of bounty.

Effect- Code

Art Gallery 1 - $10,000
Art Gallery 10 - $2,785,000
Art Gallery 2 - $30,000
Art Gallery 3 - $60,000
Art Gallery 4 - $110,000
Art Gallery 5 - $185,000
Art Gallery 6 - $285,000
Art Gallery 7 - $535,000
Art Gallery 8 - $1,035,000
Art Gallery 9 - $1,785,000