US Post Office is located at 860 6Th Ave S, Naples, FL. This location is in the Old Naples neighborhood. This business specializes in Post Offices. US Post Office is open Mon, 8:05am-5pm ; Tue, 8:05am-5pm ; Wed, 8:05am-5pm ; Thu, 8:05am-5pm ; Fri, 8:05am-5pm ; Sat, Closed ; Sun, Closed. and accepts American Express, Discover and Visa.