Archaeological excavations at the site in the 1930s produced evidence for use from the late 10th to the 15th centuries.
In addition, a drystone wall east of rock II (not extant today) could be linked to buildings here mentioned in medieval documents.
Some additional records still exist today in photographs, but they can not be put into context due to the loss of written materials in World War II.
Thermoluminescence dating in the caves support the findings.
In the main and side chamber, the last large fires were used in the 14th or 15th century (one as early as the 11/12th century).
In the Kuppelgrotte these tests have shown the last large fire to have burned in the 10th century.
One (highly uncertain) result possibly even pointed to the 8th century (actual result: 735 with a margin of error of +/- 180 years).

However, the first mention of the stones is in a document dated to around 1129, which refers to  a farm "Holzhausen or Egesterenstein".
The abbot of Werden Abbey, which owned the farm, had been passing through and was housed there.
It is possible that mass was celebrated at the Externsteine at that point.
A potential earlier mention occurs in a document dated 1093, but this is only extant in two copies from 1374 and 1380.
It records the purchase of a farm at Holzhausen including an Agisterstein by the abbot of the Abdinghofkloster (abbey) at Paderborn from a female Saxon noble called Ida.
This is deemed plausible by historians since in the 16th century the abbey still had a farmstead at Holzhausen.
However, the inscription in the main chamber of the grotto mentions a consecration in 1115 by Henrico, which is deemed to be a reference to Heinrich II.
von Werl, bishop of Paderborn from 1084 to 1127.
This implies a contradiction, since either the abbot or the bishop would be in charge of any local place of worship.
Historians have suggested, though, that this may be an indication that the abbey did not in fact claim the Externsteine for itself thus leaving them to fall into the bishop's purview.

Some authors have argued that the ecclesial carvings and alterations to the stones may suggest use of the site as a Christian sanctuary from the early 9th century.
In particular, the Externsteine relief has been the subject of debate among art historians, formerly widely accepted as of Carolingian origin (9th century), scholarly consensus has placed it in the 12th century since the 1950s.
From a stylistic point of view, historians today place the relief in the period 1160 to 1170.
Even assuming a high medieval date, the relief represents the oldest monumental relief worked into a natural rock face found north of the Alps.

In the early 13th century, temporal control of the area passed from the abbey to the House of Lippe.
From 1366, the ecclesial control of Abdinghof over a chapel at the Externsteine is well documented.
This lasted into the 17th century.
It involved a hermitage at this location, with individuals named as hermits in 1385 and 1469.
The document from 1385 also mentions an "Upper Altar", likely referring to the altar in the Höhenkammer.

There remains a contradiction between the use of the Externsteine as a simple roadhouse for travellers  and as an hermitage on the one hand and the presence of the monumental relief and the Arcosolium on the other.
These may indeed have been a reconstruction of the Holy Sepulchre.
The remains visible today indicate the possibility that the Externsteine were intended as a destination for pilgrims unable to travel to Jerusalem.
To that end many medieval churches created copies of the Holy Sepulchre.
However, it is unclear who could have built it here and why there is no written evidence of such a relatively elaborate undertaking.
Archaeological excavations at the site in the 1930s produced evidence for use from the late 10th to the 15th centuries. In addition, a drystone wall east of rock II (not extant today) could be linked to buildings here mentioned in medieval documents. Some additional records still exist today in photographs, but they can not be put into context due to the loss of written materials in World War II. Thermoluminescence dating in the caves support the findings. In the main and side chamber, the last large fires were used in the 14th or 15th century (one as early as the 11/12th century). In the Kuppelgrotte these tests have shown the last large fire to have burned in the 10th century. One (highly uncertain) result possibly even pointed to the 8th century (actual result: 735 with a margin of error of +/- 180 years).
However, the first mention of the stones is in a document dated to around 1129, which refers to  a farm "Holzhausen or Egesterenstein". The abbot of Werden Abbey, which owned the farm, had been passing through and was housed there. It is possible that mass was celebrated at the Externsteine at that point. A potential earlier mention occurs in a document dated 1093, but this is only extant in two copies from 1374 and 1380. It records the purchase of a farm at Holzhausen including an Agisterstein by the abbot of the Abdinghofkloster (abbey) at Paderborn from a female Saxon noble called Ida. This is deemed plausible by historians since in the 16th century the abbey still had a farmstead at Holzhausen. However, the inscription in the main chamber of the grotto mentions a consecration in 1115 by Henrico, which is deemed to be a reference to Heinrich II. von Werl, bishop of Paderborn from 1084 to 1127. This implies a contradiction, since either the abbot or the bishop would be in charge of any local place of worship. Historians have suggested, though, that this may be an indication that the abbey did not in fact claim the Externsteine for itself thus leaving them to fall into the bishop's purview.
Some authors have argued that the ecclesial carvings and alterations to the stones may suggest use of the site as a Christian sanctuary from the early 9th century. In particular, the Externsteine relief has been the subject of debate among art historians, formerly widely accepted as of Carolingian origin (9th century), scholarly consensus has placed it in the 12th century since the 1950s. From a stylistic point of view, historians today place the relief in the period 1160 to 1170. Even assuming a high medieval date, the relief represents the oldest monumental relief worked into a natural rock face found north of the Alps.
In the early 13th century, temporal control of the area passed from the abbey to the House of Lippe. From 1366, the ecclesial control of Abdinghof over a chapel at the Externsteine is well documented. This lasted into the 17th century. It involved a hermitage at this location, with individuals named as hermits in 1385 and 1469. The document from 1385 also mentions an "Upper Altar", likely referring to the altar in the Höhenkammer.
There remains a contradiction between the use of the Externsteine as a simple roadhouse for travellers  and as an hermitage on the one hand and the presence of the monumental relief and the Arcosolium on the other. These may indeed have been a reconstruction of the Holy Sepulchre. The remains visible today indicate the possibility that the Externsteine were intended as a destination for pilgrims unable to travel to Jerusalem. To that end many medieval churches created copies of the Holy Sepulchre. However, it is unclear who could have built it here and why there is no written evidence of such a relatively elaborate undertaking.
Externsteine