The Church of St. Leonard (Czech: Svatý Linhart) used to stand on a hillock above the medieval settlement of Thiergarten (Czech: Obora, Latin: Ortus ferarum, English: Game-Park), which was apparently a service village in a hunting game-park belonging to Loket Castle in the Middle Ages.
The village of Obora is first mentioned in 1325 in connection with the award of the feoff to Kojata of Otnavice who subsequently built a manor near the village – i.e. the game-park fortified manor is still apparent today (Kellerberg). Initial archaeological research was conducted on the site at the turn of the 1940s and in the 1950s by means of semi-amateur excavations. Unfortunately, no documents concerning the research exist. In 1989, two archaeological probes installed by the Karlovy Vary Museum (Jiří Klsák) ascertained the remains of destroyed stone structures and medieval pottery dating back to the period between the 14th and 16th century. The church itself is first referred to in 1246 when King Václav I (also denoted as Wenceslas I of Bohemia) donated it along with the churches in the village of Olšová Vrata and the former village of Vranov to the Order of the Knights of the Cross with the Red Star. In the mid 14th century, the village of Obora and the church became the property of the new town of Karlovy Vary.
The decay of the church is the result of the continuous depopulation of the village and the loss of importance of the site in the late 15th century when the town in the valley, enjoying numerous privileges awarded by its founder Emperor Charles IV, was gradually becoming the centre of the area.
Owing to the location of the mysterious ruins in the Karlovy Vary spa woods near the road to Horní Slavkov and the relationship with the town itself, the locality has been the subject of much research since the 18th century. In 1772, for example, a local spa physician, David Becher, noticed that white thermal tuff, among other material, had been used for the construction of the church.
The church has a simple ground plan, a right-angled oblong aisle with dimensions of 1250 by 1000 centimetres, which is adjoined by a right-angled square presbytery in the east with dimensions of 800 by 800 centimetres. The masonry was 120 centimetres wide and it was coursed.
Archaeological research in the church was initiated by the Karlovy Vary Museum (Jiří Klsák) 1989. Archaeological probes were used to determine the floor level and the condition of the interior details. In 1990, archaeological work continued by removing debris from the interior and by cleaning the excavated area down to the level of the last floor layer. The floor comprised of a mortar layer, in which square brick tiles were laid diagonally to the church axis in the presbytery and in parallel to the axis in the main aisle. The exposed walls also rendered some quite interesting findings. The quarry stone was jointed with lime mortar with an admixture of thermal tuff, and a few rare remnants of thicker smoothened lime plaster were discovered on the walls. Fragmental foundations of a triumphal arch were confirmed between the presbytery and the main aisle, with fragments of a modelled stone sill between them. Conical entrances were uncovered in the north and south wall, whereas the northern entrance faced the village and the southern entrance led to the adjoining cemetery. Well-preserved foundations of two side altars were unearthed under debris in the northeast and southeast corners of the main aisle. The existence of the main altar was confirmed in the presbytery, however, in a very poor condition despite all expectations.
The grave of a man buried with two children was also discovered in the main aisle that year.
In 1991, interior research continued in the presbytery. A quite remarkable finding was made during the research. Skeleton remains of a young woman were discovered in the area of the main altar, partially covered by the debris from the altar. The woman's skeleton lay on the left side in a squatting position, without any specific orientation. The position of the hands and feet indicated that they had been bound. The grave was dated back to the turn of the 16th and 17th century based on the findings. It is beyond any doubt that the archaeologists uncovered a scene of violence from the past, perhaps dating back to the times when the region was not a very safe place to live in. Subsequently, research continued in the southern part of the church where the existence of a medieval cemetery was confirmed by the skeleton remains. Dozens of other buried skeletons were discovered in 1992. The buried remains often lay in four or five layers on top of each other, frequently damaging one another. This bespeaks of burials taking place for many decades, as well as a lack of space. The graves were simple, without any charitable gifts and with more or less secondary and therefore, difficult to date findings.
The discovery of an annex adjoining the southern presbytery wall (possibly a dead house) was also associated with burials. Among the many findings discovered at the Church of St. Leonard, were several dozen coins, including some quite interesting Bohemian bracteate hellers from the 14th century, as well as a bone carved miniature of Saint Catherine, a torso of Jesus Christ, and particularly a large quantity of iron votive items, zoomorphic and anthromorphic, which were put on the Altar of St. Leonard as a plea for help, are definitely worth mentioning.
In 1998 and 1999, the ruins of the Church of St. Leonard were conserved thanks to the diligent care of the town of Karlovy Vary and the site was landscaped in a reverential manner to ensure that the condition of the historical monument corresponds to its significant role in the history of Karlovy Vary. The importance of the historical site was further enhanced by the extensive trimming of the surrounding forest stand in 2007.