La Torre-La Janera megalithic site
La Torre-La Janera megalithic site is located in the municipalities of Ayamonte and Villablanca in the province of Huelva, Andalusia. It was discovered when in 2018 a farmer intended to prepare the land to cultivate avocados and in view of the archaeological potential of the site the local council demanded a survey to be made. It is considered to be one of the largest megalithic site in Europe with over 500 standing stones. Location    
The site is in the municipalities of Ayamonte and Villablanca at about 2.5 km to the west of the Guadiana river and some fifteen km from the Atlantic in the south. It was built though near the coastline as some 6000 to 4000 years ago, the sea level was two meters higher. The megaliths are in about 90 hectares that are part of a 600 hectare large rural estate. Discovery 
The megalithic site was discovered in 2018 as in view of the archaeological potential of the site, the local council decided to execute a survey through which menhirs, dolmens, burial grounds were unearthed. Following the Regional Government of Andalusia divided the area into four divisions mostly reserved for archeological investigations, and agricultural use is only permitted on about 220 hectares of the site. It has at least 6 surrounding terraces and a quarries for greywacke  and conglomerate

Description 
La Torre - La Jarena is described as the largest megalithic site in Europe, with hundreds of standing stones, several dolmens and geometric alignments. Dolmens 
There are several dolmens on the site, who stand out for the small size of their chambers. Some stand alone, others in groups and they were up to half a meter high. Forming circles or ovals, the several dolmens diameters spanned from six to seventeen meters and forty-one coffins hewn in stone have also been found within them. Standing stones 
So far 526 standing stones were revealed during the survey, either still standing or lying on the surface. Most of the ones in an alignment of a geometric form are lying on the ground. Geometric alignments 
There are two alignments in the shape of a letter, one in the shape on U or horseshoe, and another one in shape of an H. The third one is an elliptic one. They seem to have been created and are assembled on a hilly surface. The elliptic one is within an area of almost 2 hectares and 200 meters long in its long diameter. It has at least six surrounding terraces and a quarry for Greywacke. The H spans 100 meters length, 80 meters width and is composed by three interconnected walls which include six menhirs. History   
It is assumed that the first megaliths were erected in the 5th or 4th Millenia BC while most constructions are thought to have been erected between 3750 and 3500 BC. Eucalyptus have been planted in the region, and the area has also been affected by the construction of wind farm in 2008. References 

Archaeological sites in Andalusia
Megalithic monuments in Spain