The roman Gate can be visited
Roman Gate Dalkingen

The Roman Gate Dalkingen is an ancient monument on the Upper Germanic-Rhaetian Limes in Baden-Württemberg. It was expanded into a triumphal arch under Emperor Caracalla. Since 2005, it has been part of the UNESCO World Heritage Site.
History+
The history of the Limes Gate Dalkingen dates back to 130 to 135 AD, when a wattle fence with a wooden watchtower was erected under Emperor Hadrian. Around 161/169 AD, a wooden palisade with a first wooden Limes Gate was built. In the early 3rd century, during the reign of Septimius Severus, the stone Limes wall began to be constructed. Under Emperor Caracalla (212 to 217 AD), the stone Limes Gate was completed, and its south facade was transformed into a triumphal arch-like show facade. This transformation is associated with a visit by Caracalla in 213. Archaeological finds, including fragments of a larger-than-life armored statue, support this assumption. The complex was rebuilt several times and also served a border guard.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/w/index.php?title=Datei:Dalkinger_Tor_neu_1.jpg&filetimestamp=20100730155655&
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 48.9269, 10.1556