[1] Since 2005, the ancient border passage, which was developed into a triumphal gate under Emperor Caracalla, is a UNESCO World Heritage Site, together with the entire Roman Limes complex in Germany.

It is also part of the open-air museum of the Rhaetian Limes, which was established in 1972 and also includes the nearby Buch fort [de; ceb][2] and its civilian settlement.

Today, the field and hiking trail from Schwabsberg to Dalkingen, which takes the course of the Limes, passes to the north of this former border crossing.

This was followed in 1886 by a report by the archaeological pioneer Karl August von Cohausen [de] (1812-1894), who also presented the first reconstruction of the Limes Gate.

[9] It was only in the course of land consolidation that the Baden-Württemberg State Office for the Protection of Monuments [de] carried out another comprehensive assessment from 25 September to 23 November 1973 and from 1 June to 30 July 1974 under the direction of Planck.

[10] With the help of modern working methods, the building could then be interpreted as a repeatedly remodelled Limes gate with adjoining rooms for a border guard.

According to a fragmentarily preserved inscriptional source, the Acta Fratrum Arvalium,[13] the emperor crossed the Rhaetian border on 11 August 213 in battle against the Germanic peoples.

In January 2003, the school and culture committee of the Ostalbkreis district voted in favour of the future preservation of the site under a protective structure.

[18] The 16 metre-high steel and glass construction, which cuts through the oldest wooden predecessor of the Limes Gate, encases parts of the more recent antique structure over an area of 23 × 21 metres.

The construction work carried out in the summer of 2010 not only protects the covered ancient substance but also reduces the renovation and maintenance costs previously required.

[20] In addition to Planck, the Bavarian state conservator C. Sebastian Sommer [de] (1956-2021) also supported this dating approach concerning the construction of the entire Rhaetian and "Anterior Limes".

[22] As the isolated post holes found suggest, a Roman construction team initially erected a simple wattle fence along the intended boundary line as an obstacle to approach.

The post settings found along the south-west side of the tower would thus have obscured the view of the gateway from the south[23] and could be addressed as an additional safety measure.

In 1969, semi-circular split oak trunks were recovered as parts of the wooden Limes palisade on the southern edge of Schwabsberg in the area of the Jagst lowlands, which had been marshy since ancient times.

There, on the border to the province of Germania superior, this wood was used to build a fortification that was probably erected in 164 CE (see Kleindeinbach small fort [de]).

[20] The fence was removed; around three metres to the north, a tightly packed wooden palisade of oak poles was built, for which a narrow trench had to be dug.

In the lowest filling of its post trenches, which were unusually deep at up to 1.1 metre, a well-preserved sestertius from the reign of Emperor Antoninus Pius (138-161) was found alongside some pottery shards.

Research has identified certain similarities between the Limes gate and the small milestone forts [de] on Hadrian's Wall in northern England.

[32] While the course of this military and trade route can be narrowed down in the area of the former Roman Empire, its traces in the unoccupied part of Germania are no longer detectable.

This is indicated, among other things, by dendrochronologically examined timbers from the substructure of the wall at Fort Dambach [de; ceb], which were felled in the winter of 206/207 CE.

The Limes wall coming from the south-east now ran directly across its northern flank before it cut the dismantled wooden gateway in the middle and bent to the west just within a few metres of it.

In the centre of this front, the researchers were able to make out the imprint of a massive swelling stone on the ground in the direction of the Limes wall, which illustrates its function as a passageway.

The largest preserved parts are several pteryges (textile or leather strips) of a breastplate and a sword pommel decorated with an eagle's head.

A stylistic analysis of all the fragments led to the conclusion that the statue was older than the Limestor itself and was created in the late reign of Emperor Hadrian (117-138) or the first years of his successor Antoninus Pius (138-161).

The archaeologist Dietwulf Baatz [de] (1928-2021) first raised objections to Planck's interpretation of construction phase 6 as a pompous Limes gate in 1993.

The southern part of the pit was bordered by a mortarless wall made of quarry stones, in which there were slits for the air supply channels.

This was a previously unearthed square stone building measuring 20 × 20 metres, which archaeologist Stephan Bender [de] (1965-2019) classified as a sanctuary or, more likely, a small Roman fort.

[40] However, as there is no evidence of an Alamanni attack between 233 and 234 in the nearby vicus of Buch fort, the Germanic raid could have taken place in the early summer of 254 CE.

[42] The decoration of this chape with heart-shaped cut-outs was typical of Roman military equipment from the end of the 2nd century, when the spatha had become the main weapon in close combat.

Many pottery fragments were catalogued from the gate,[45] although late terra sigillata from Rheinzabern (Tabernae [de; ca]) and pots with heart- and sickle-shaped profiles are completely absent.