Luxor Temple in Egypt has a single obelisk in front of its entrance gate, but the gate was built with two. The missing one didn't fall: it has stood in the Place de la Concorde in Paris since 1836.

• ✓DRAC Île-de-France, L'Obélisque de Louxor, plus ancien monument de Paris (culture.gouv.fr)
• ✓Musée national de la Marine, Le voyage de l'obélisque press kit (2014)
• ✓A. Lebas, L'obélisque de Luxor (1839)
• ✓Wikipedia, Cairo Citadel Clock (citing Al-Monitor 2021-10-06, Egypt Today 2021-01-05)

This temple gate in Luxor, Egypt, has one obelisk. It was built with two. The other one didn't fall. It's in Paris. In 1830, Egypt's ruler gave it to France, and France built a ship just to carry it. It took almost three years to get the nearly 250-ton stone to Paris, where it still stands in the middle of the city. In return, the story goes, Egypt got a French clock. It barely ever worked. But Egypt's ruler had offered France both obelisks. France never came back for the second one, and didn't give up its claim until 1981. So for a hundred and fifty years, the obelisk still standing at this gate belonged to France, on paper. Subscribe for a fact every day.