Police are stepping up searches in Windsor as the town prepares for the funeral of the Duke of Edinburgh.
Thames Valley Police has deployed officers and dogs to carry out specialist searches across the town.
The force said an increased police presence and "not so visible security measures" were to "keep everyone safe" during the period of national mourning.
Police have been searching phone boxes, drains and bins, along with carrying out patrols in the town centre, the Long Walk and Home Park.
The force is also using Automatic Number Plate Recognition (ANPR) to monitor vehicles travelling in and around the town, and checking lorries.
The royal family is set to gather for the duke's televised funeral, taking place behind the walls of the castle, in St George's Chapel.
The event has been scaled down due to Covid-19 restrictions.
Members of the public have also been asked to stay away from the castle.
John Story, mayor of Windsor and Maidenhead, said: "We have to ask everyone to put theirs and the health and safety of others at the top of their list of priorities and not come into Windsor.
"The whole of the funeral, including the ceremonial procession, is taking place inside the castle walls."
He added if members of the public come to Windsor "there will be nothing to see".
A Thames Valley Police spokesman said: "We would ask that the public respect the royal household's wishes and the government advice by not visiting royal residences or gathering in public, in order to protect each other and reduce the risk of coronavirus transmission.
"Additional officers will be patrolling Windsor town centre along with the surrounding area to help provide reassurance and keep local residents, businesses and people safe."