Where is the radiator cap on a 1999 Lincoln town car?

The radiator cap on a 1999 Lincoln Town Car is located on the top of the radiator, at the front of the engine compartment. It's usually a black plastic cap, sometimes with a pressure relief valve visible. Because the engine is relatively large, it might be slightly tucked in, but it's always on top of the radiator itself and relatively easy to spot once you've opened the hood.