Dogs are welcome at Fort DuPont State Park, previously an active military base from the civil war all the way to World War II. One of the most interesting things to do at Fort DuPont State Park is to take on the River View Trail alongside the Delaware River. You'll be able to spot the places where canons and guns once lined this pathway. The fee for entering the park is $4 for in-state visitors and $8 for out-of-state visitors. The park is open every day of the week from 8am until sunset.