Nestled within Fort Lee, VA, is an ordnance museum inaccessible to the public. Within this museum sits a German Krupp K5 railgun, named Leopold. It took every bit of a 14mm lens to get the full rail gun in the image, as quarters are tight in the museum and it hugs a side of the building. The gun itself used to be housed up at Aberdeen proving grounds but was moved to Fort Lee. A little info on the gun from wikipedia:
Krupp's K5 series were consistent in mounting a 21.5 metres (71 ft) long gun barrel in a fixed mounting with only vertical elevation of the weapon. This gondola was then mounted on a pair of 12-wheel bogies designed to be operated on commercial and military rails built to German standards. This mounting permitted only two degrees of horizontal traverse. The carriage had to be aligned on the rails first, with only minimal fine leveling capable once halted. Hence the gun could only fire at targets tangential to an existing railway track.
To track targets needing greater traverse either a curved length of railway was used with the gun shunted backwards or forwards to aim; a cross-track was laid with the front bogie turned perpendicular to the rest of the gun and moved up and down the cross-track to train the weapon; or for 360 degree traverse, the "Vögele Turntable" could be constructed, consisting of a raised rail section (the "firing bed") carrying the gun, running on a circular track with a central jack to raise the gun during traverse and to take some of the enormous weight.
The main barrel of the K5 is 283 mm (11.1 in) in calibre, and is rifled with twelve 7 mm (0.28 in) grooves. These were originally 10 mm (0.39 in) deep, but were made shallower to rectify cracking problems.