A rather rare thing is a natural cave used to build a road or railroad tracks through. To do this the cave has to have two entrances, be big enough and the location has to be somewhere, where a road is needed. It is easy to understand that this happens very rarely.
Caves of this type have an enormous benefit: you can visit it by driving through! On the other hand, it is rather hard to see much of the cave if you drive through with maybe 80 km/h. This is also the reason why some are now closed to road traffic.
Grand Arch, Jenolan Caves, Australia.
穿龙岩 - Chuanlong Dong, Guanxi, China
江州天生桥 - Jiangzhou Natural Bridge, Guanxi, China
社更穿洞 - Shegeng Through Cave, Guanxi, China
Grotte du Mas-d’Azil, France.
Grotta di S. Giovanni di Domusnovas, Italy.
Natural Tunnel, U.S.A.
La Cuevona, Spain.
雄橋 (Ohashi or Onbashi Bridge) in Taishaku Gorge, Japan.
Hanyama No. 2 Tunnel, Japan
Pohara Natural Bridge, New Zealand
Tunel Ponikve, Bosnia and Herzegovina
Dobroselički Prerast, Serbia