More than a dozen tall towers line the beaches of Delaware's seaside state parks. To all outside appearances they look like World War II-era military-style bunkers, and a closer inspection reveals that this is exactly what they are.

These silent sentinels are left over from a time when the entire world was at war. Built during the 1930s, these observation towers were only supposed to last for a few decades. But in areas such as Delaware's state parks, where seaside development couldn't encroach, the towers still stand.

Most of the towers are about 70 feet high, though they vary in height from 40 to 90 feet. They are about 17 feet in diameter and have walls that are 1 foot thick. Observation slits face the sea and cover an arc of 240 degrees. A single door at the base of the towers faces away from the ocean.

The purpose of the towers was to watch the Atlantic coast, particularly the approaches to the Delaware Bay, and direct the fire of in-shore artillery batteries. The towers and guns were manned 24 hours a day throughout hostilities with Nazi Germany. Despite this vigilance, the guns were never fired.

Today, the towers are abandoned and a state park ranger says the metal stairways inside the towers have all been cut to prevent anyone from climbing inside. The doors are padlocked and checked periodically to ensure that no one has been inside.

Vandals have covered the lower 10 feet of many of the towers with spray-painted obscenities and other idiotic graffiti.

The towers can be seen in Cape Henlopen State Park, Delaware Seashore State Park and Fenwick Island State Park. One of the towers in Cape Henlopen State Park is open to tourists during daylight hours.