Once a year, usually in or around the month of September, historical monuments, notable buildings and sites of interest across Europe open their doors, rendering places that are normally off-limits to the general public fleetingly accessible. When a knowledgable guide is added to the mix, a visit can be as informative as it is enjoyable. Here’s a look at how several countries will be celebrating their cultural heritages this year.

Germany: The Tag des offenen Denkmals, or Day of Open Monuments, is an annual event held on the second Sunday in September each year. On the day, historic monuments across the land are open to the public free of charge. The theme of the day changes each year; in 2024, “True Signs: Witnesses of History” gives form to the openings and guided tours planned for Sunday, Sept. 8. The event takes place within the larger framework of European Heritage Days, a European-Union wide initiative designed to build awareness and appreciation of exceptional and historically significant properties.

With thousands of properties suddenly accessible, it can be difficult to know where to begin. Sites close to where the U.S. military has or had a presence might include the following:

Heidelberg

A redevelopment project known as paraSol will soon transform a building formerly owned by the U.S. military on Campbell Barracks into housing units. Those interested in seeing the building in its original condition are offered a tour at 1 p.m. Coffee and cake will be served onsite. The three-story building is found at Adelheid-Steinmann-Str. 2, 69126 Heidelberg. Online: parasol-heidelberg.de/aktuelles

Kaiserslautern

Burg Hohenecken is a castle ruin perched high on a hill above a part of town also known as Hohenecken. Built sometime between 1150 and 1250, the structure was destroyed in 1688 as part of the Palatinate War of Succession. Reaching the castle, located at Schlossstrasse 10, 67661 Kaiserslautern, entails a steep uphill walk. Opening hours are noon-5 p.m. Online: tinyurl.com/3bcukwa6

Stuttgart

The Gottlieb Daimler Memorial, found in the Cannstatt district of town, is a property once owned by the engineer credited with the invention of the petroleum-fueled engine. The property consists of a workshop, garden house and ruins of the family’s villa. On Sept. 8, the Daimler Tower, a circa-1894 building offering murals and a viewing platform, will be open. The tower is located at Taubenheimstr. 13, 70372 Stuttgart. Online: tinyurl.com/yc5k6fs4

Wiesbaden

The Dotzheim train station, from which a steam train once regularly traveled to Bad Schwalbach, opens its waiting rooms and signal box housing the railroad’s levers and other equipment used to coordinate railway transit at Moritz-Hilf-Platz 2, 65199 Wiesbaden. Literary readings (in German) complement the open premises. Online: aartalbahn.de

In the rotunda of the Biebrich Palace is found a hall where weddings and other special events regularly take place. At 6:30 p.m., a concert will be given by the students of the Wiesbaden Music Academy. The two-hour program contains music from the German Romantic period, with works from Weber, Schuhmann and Brahms. The palace is located at Rheingaustr. 140, 65203 Wiesbaden-Biebrich. Online: tinyurl.com/mu782cku

Malta

With this tiny but history-rich island nation organizing its European Heritage Days later in the year — October 4-14 — there might yet be time to plan a trip there. A highlight of Malta’s participation is its annual Notte Bianca festival, scheduled to take place Oct. 5 in 2024. For one night, the island’s capital Valletta is a city transformed by live performances, art installations and late-night openings. Churches, palaces, public buildings and other spaces host more than 60 forms of artistic expressions, ranging from classical performances to saucy, adults-only fare. Online: festivals.mt/nb

Netherlands

Open Monumentendag — held every second weekend of September — sees some 4,000 historical buildings and sites open to the public free of charge. Many of these places will host activities such as exhibitions, musical performances and guided tours.

Things to do on the weekend of September 14-15 in Amsterdam might include taking a tour of the premises of the ARTIS aquarium set to open in 2026; exploring the dry docks of the Damen Shipyards; or letting the kids take part in a challenge to build the strongest bridge out of LEGO blocks. Online: openmonumentendag.nl

United Kingdom

Open House London in an initiative in which diverse architectural landmarks allow visitors into privately owned or otherwise restricted properties. From Sept. 14-22, explorers can enjoy access to seldom-open sites including residences, cemeteries, breweries, distilleries, greenhouses and more.

Open City, the charity that runs the festival, also offers guided walking tours, to include several exploring London’s public houses, better known as pubs. One such tour takes visitors through a mix of curious and historically notable pubs starting at 6:30 p.m. Sept. 25. The two-hour tour costs 17.95 UK pounds, and pre-registration is essential. Online: open-city.org.uk