Russia is planning a second major military base near the border with Ukraine, where NATO accuses Russian troops of helping pro-Moscow separatists fight Kiev's forces.
The new base will house 5,000 soldiers and heavy weaponry, according to public documents and people working at the site.
It is further east than one under construction in Belgorod region reported by Reuters earlier this month but still close to the border with separatist-held parts of Ukraine's eastern Luhansk region, where there has been heavy fighting.
The bases are part of a Russian military buildup along a new line of confrontation with the West, running from the Black Sea in the south to the Baltic in the north, which carries echoes of the Cold War-era "Iron Curtain".
Russia has also increased its military presence in Syria.
NATO and the pro-Western government in Ukraine say Moscow uses bases on the border with the former Soviet republic as staging posts to send troops across into areas where almost 8,000 people have been killed since April last year.
Moscow had annexed Ukraine's southern Crimea peninsula a month earlier but denies having any troops in eastern Ukraine.
The documents show the Russian defence ministry intends to turn an old military depot in the town of Boguchar, in Voronezh region, into a major base with dozens of buildings and special facilities for more than 1,300 armoured vehicles and ammunition.
The new base, with a dozen barracks with space for 5,210 troops, warehouses for rockets, an infirmary, swimming pool and large training complex, will be 45 km (28 miles) from the Ukrainian border.
According to tender documents published on the Russian government website zakupki.gov.ru, the ministry plans to transfer a motorized rifle brigade from Nizhny Novgorod, in north-west Russia, to Boguchar along with troops trained in how to respond to nuclear, biological and chemical attacks.
At the Boguchar depot, a soldier said some had already arrived. "The guys from Nizhny Novgorod are already here," he said, declining to give his name.
Guards would not allow the reporter to enter the depot, and the officer in charge there refused to speak to Reuters.
From the barbed wire fence that marked the perimeter, no fresh signs of construction could be seen, only a half-built building on which work appeared to have been abandoned some time ago, and a ramshackle barracks.
Dozens of vehicles with servicemen, including military trucks, were driving on the road leading to the depot. The road surface had marks left by tank tracks.
The site was home to a tank division until 2009 when the division was dismantled, and the base was subsequently used to store military equipment, according to Russian media reports.
The Russian defense ministry did not reply to written questions from Reuters about the purpose of the new base it plans to build at Boguchar and whether there was any connection to the Ukraine conflict.
The war in Ukraine has dragged relations between Russia and the West to their lowest level since the Cold War.
Besides the plans for the two new bases in southern Russia, the Kremlin has moved military hardware to its Baltic enclave Kaliningrad, approved a military air base in Belarus last week, and it is beefing up its military presence in Crimea.
Russia has pulled out of the treaty on Conventional Forces in Europe, a post-Cold War pact that limits the deployment of troops in Europe, so it is free to move extra troops and hardware to its western border.
According to the procurement documents, the defense ministry plans to complete initial construction and installation works at the Boguchar base by April 29, 2016.
The ministry intends to use the base to train soldiers on artillery and man-portable air defense system.
On top of that, the base will include a headquarters with a communications node, a huge dining room, a sports complex with tennis and badminton courts, and kennels with room for 30 dogs, the documents showed.
Fighting between Ukrainian government forces and separatists in Ukraine's eastern Donetsk and Luhansk regions has subsided since Sept. 1, when the Ukrainian parliament backed giving more autonomy to rebel-held areas in line with a peace deal.
But disagreements over local elections envisaged by the deal have renewed tension.