How should a firewall be deployed? I'm confused. ISP > Firewall > Router > LAN or ISP > Router > Firewall > LAN

Like the question says:

ISP > Firewall > Router > LAN ISP > Router > Firewall > LAN?

We have several routers and devices at the "Edge" but I would think you should have the firewall at the edge then all devices behind it for better security. Correct me if I'm wrong.

Thanks!