An observation deck on the 21st floor of Osaka’s Sakai City Hall provides visitors with a bird’s-eye view of the surrounding area. In the midst of the urban jungle a few kilometers away, a large patch of greenery in the distance looks out of place amid the sea of modern buildings, like a public park that managed to escape development.

Up close, however, the green oasis turns out to be not a park but the burial mound, or kofun, of Emperor Nintoku. Officially known as Daisen Kofun, it’s the centerpiece of what is known as the Mozu-Furuichi Kofun Group.

After years of lobbying efforts by Osaka Prefecture and the central government, UNESCO announced in July that 49 kofun in the ancient group in and around Sakai would be added to its World Heritage list.

The city hopes the latest World Heritage site in Japan, which dates back to the third and sixth centuries, will prove to be an international tourist magnet. Especially since Sakai lies between Osaka and Kansai International Airport.

Some kofun have been designated as ryōbo, or graves of the ancestors of the Imperial family, although historians and archeologists continue to debate whether those kofun actually contain the said individuals.

UNESCO acknowledges that debate. But it says the burial mounds have a lengthy history and thus recommended they be designated a World Heritage site.

“While 160,000 kofun are found throughout Japan, the Mozu-Furuichi Group represent and provide exceptional testimony to the culture of the Kofun Period (around the end of the third century to around the seventh century) of Japan’s ancient history,” UNESCO concluded.

With their World Heritage status now confirmed, the controversy Sakai now faces regarding the kofun is not related to ancient history but the problems of modern urbanization.

World Heritage sites are supposed to have buffer zones surrounding them. Not just to protect them from damage due to human encroachment and natural disasters, but also to help preserve the historical and cultural atmosphere.

This means there will be restrictions on commercial and residential building heights and designs close to the site, as well as on the kind of outdoor advertising signs businesses can put up.

The management plan for the Mozu-Furuichi group, submitted to UNESCO by the Imperial Household Agency, Osaka Prefecture, Sakai and two other cities where the kofun are located, notes that a priority zone right beside the kofun has been established where outdoor advertisements on surrounding buildings are, in principle, prohibited.

In 2016, Sakai passed an ordinance that established a priority zone 100 meters around each of the Mozu and Furuichi kofun that prohibited large outdoor signs on buildings and set tight regulations on the size of smaller forms of advertising, such as signboards in front of shops. The city offered each business within a priority zone financial assistance in removing their signs.

Back then, the city calculated there were 138 signs within the priority zone that needed to be taken down. Last month, Sakai Mayor Hideki Nagafuji said that, at present, there were still 58 signs standing.

“I understand the signs were there before the kofun became a World Heritage site. We’ll continue to seek the cooperation of those businesses,” he told local reporters.

That, however, could take time, and Nagafuji gave no deadline for those signs to be removed. The mayor, at this point, prefers persuasion to punishment for violating the ordinance.

Sakai’s move reflects a larger problem of modern, crowded cities placing new urban development rules on residents who have been living right beside ancient cultural sites for years or decades but now face having to adjust to the rules governing a World Heritage site.

Kyoto, with its 17 World Heritage sites, already has an ordinance governing outdoor advertising and displays in specially designated zones near them. Violators can be fined and the city is using the ordinance to crack down on more than just large billboards or rooftop signs.

In May, Kyoto ordered a 12.5-meter inflatable kokeshi (traditional Japanese doll) that had been installed close to Heian Shrine to be taken down on the grounds that it disrupted the scenery of the surrounding area.

The display was part of a promotional exhibition that the city itself was involved with. However, once erected, officials changed their minds. As a compromise, the doll was allowed to be displayed lying down.

Sakai does not yet have such strict regulations within the Mozu-Furuichi Kofun Group area. UNESCO noted in its recommendation for listing that more than 80,000 residents live within the buffer zones of the 49 kofun.

Osaka Prefecture, Sakai and the other two cities where the kofun are located have made efforts to buy private land within the buffer zones in order to make it easier to conserve and protect the views of the sites.

In the meantime, tourists from Japan and overseas are starting to visit some of the kofun, especially the Daisen Kofun. Foreign-language explanations, virtually nonexistent a decade ago, and recommended walking routes have been drawn up. Discussions are underway as to how to most effectively shuttle visitors to and from the Mozu and Furuichi tumulus clusters, which lie about 10 kilometers from each other.

Given there is little that can be seen at most of the kofun except the surrounding forested areas or moat because entry into the mound itself is forbidden, attracting people with interesting explanations is all the more important, especially when it comes to international tourists.

With some residential areas and businesses lying only a few meters from the sites, ensuring visual distractions like outdoor signs are kept to a minimum is not only in the interests of preserving the Mozu-Furuichi Kofun Group in terms of cultural atmosphere. It’s also a measure likely to prove more attractive to tourists who arrive at the sites expecting to be immersed in a quiet, traditional atmosphere, without eyesores like garish outdoor signs that are visually jarring and spoil the scene for an otherwise perfectly framed photograph.

When those photos are shown to friends and family back home, how sign-free the background is may help them decide if they want to spend time during a visit to Japan to drop by the Mozu-Furuichi Kofun Group in order to experience the burial mounds for themselves.