Police are investigating after a wall at Shoreham Fort was daubed with graffiti.
The criminal damage at Forthaven is believed to have happened sometime between 5.30pm on March 26, and 3.30pm on March 29.
Similar graffiti has also been discovered on the brickwork.
PC Mike Harvey said:
“The fort is an Ancient Scheduled Monument and any crimes committed on the site which directly affect it are treated as aggravated heritage crimes.
“If we find anyone committing such offences at the site, they will be dealt with robustly and appropriately.
“We would also like to hear from anyone who witnessed the incident or has any information about it.”
Anyone with information is asked to contact police online here, or call 101, quoting reference number 829 of 29/03.