Gibbon’s Division served as a member of the Second Corps in the Army of the Potomac. The division was commanded by Brigadier General John Gibbon (April 20, 1827 – February 6, 1896), a career United States Army officer who fought in the American Civil War and the Indian Wars. Gibbon was promoted to command the 2nd Division, I Corps at the Battle of Fredericksburg, where he was wounded. At the Battle of Gettysburg, he commanded the 2nd Division, II Corps and temporarily commanded the corps on July 1 and July 2, 1863, while Maj. Gen. Winfield S. Hancock was elevated to command larger units. Gibbon was a mainstay during the entire Civil War, having participated at numerous and infamous battles. I suppose as a reward to all of this, he was one of three commissioners for the Confederate surrender, at Appomattox Court House, Virginia at the home of Wilmer and Virginia McLean. Gibbon even attended the opening of the National Cemetery and was there for Lincoln's famous Gettysburg Address. John Gibbon died in Baltimore, Maryland, and is buried in Arlington National Cemetery. In addition to his famous and influential Artillerist's Manual of 1859, he is the author of Personal Recollections of the Civil War (published posthumously in 1928) and Adventures on the Western Frontier (also posthumous, 1994) along with many articles in magazines and journals, typically recounting his time in the West and providing his opinions on the government's policy toward Native Americans. On July 3, 1988, the 125th anniversary of the Battle of Gettysburg, a bronze statue of John Gibbon was dedicated in the Gettysburg National Military Park, near the site of his wounding in Pickett's Charge.
The Gibbon's Division - US Division Tablet, also known as the Army of The Potomac, 2nd Corps, 2nd Division Tablet, is located along South Hancock Avenue @ Cemetery Ridge, on the right or southeast side if traveling northeast; the monument faces the west. The marker is just before a bend in the road which then turns into a straightaway, heading due north and to the U.S. Regulars Monument and the Copse of Trees, the site of the High Water Mark of the Rebellion. 
This part of the road is one way and you cannot get the monument traveling south. Parking is available everywhere along Hancock Avenue, on both sides of the road. This area represents the best of what Gettysburg has to offer, both historically and monumentally and is a beehive of activity. Expect to stay well over an hour for this part of the battlefield. I stayed for four hours. Be sure to keep vehicles off the grass or you will be ticketed by park police. I visited this monument on Monday, August 13, 2012 @ 3:50 PM. I was at an elevation of 576 feet, ASL. I used a Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
Draw the Sword, with descriptive help from the NPS site, offers the following description: Monuments are rough-hewn monoliths, 4 feet 2 inches x 2 feet x 7 feet in height, consisting of Winnsboro, South Carolina granite. Bronze inscription tablet, 3 feet 8 inches x 3 feet 6¾ inches, is affixed to the polished face of the monolith. Corps insignia, a bronze Maltese Cross, is excised & polished at top of tablet. One of 22 Union division monuments that describe the movements and itinerary of each division of the Army of the Potomac. Designed by E. B. Cope. The trefoil symbol of the Second Corps appears at the top of the tablet, just above the main inscription, on a separate piece of metal. The inscription on this tablet reads:
Army of the Potomac
Second Corps
Second Division
Brig. General John Gibbon, Brig. General William Harrow
First Brigade Brig. Gen. Wm. Harrow, Col. Francis E. Heath
Second Brigade Brig. Gen. A.S. Webb
Third Brigade Col. H.J. Hall
One Co. Mass Sharpshooters
July 2 Arrived between 6 and 7 a.m. and went into position on line between Cemetery Hill and Round Top Third Division on right and First Division on left. Second Brigade constituting the right Third Brigade the left and First Brigade in reserve. Sharp skirmishing continued through the day and Artillery fire at intervals until near sunset when the Third Corps having been driven back Wright's Georgia Brigade furiously attacked the Division and was repulsed with loss including many prisoners. The Twelfth Corps coming to the support of the left.
July 3 Artillery firing until 9 a.m. and sharp skirmishing during the day. At 1 p.m. Confederates concentrated the fire of over 100 guns on the Second and Third Divisions and after two hours of uninterrupted firing charged with a force of over 15,000 Infantry which was repulsed with great loss of life prisoners and flags. The Division remained in position with no further engagement than skirmish firing.
Casualties including Division Staff and unattached troops. Killed 25 officers 319 men. Wounded 105 officers 1097 men. Captured or missing 6 officers 95 men. Total 1647
There are hundreds of non-sculpted monumentation for the various Regular Union (Army of the Potomac - Federals) units & "Regular" Confederate units engaged at Gettysburg from July 1-3, 1863. There are about 10 different variations of tablets, markers & monoliths by my reckoning. Six designs represent brigade (2), division (2), corps (2), & army headquarters (only 2), each different in a subtle way so as to distinguish between armies. Battalion/battery/advance position markers & regimental monuments for U.S. Regulars & Confederate have their own distinct design (2), bringing the total to 10 designs at the battlefield. The bronze tablets (these ones, too) were created by Albert Russell & Sons Co. of Newburyport, Mass. The granite bases which accompany the various tablets were created by the Van Amringe Company from Boston, Mass. The cast iron tablets were manufactured by Calvin Gilbert. The 1910 Gettysburg Commission report lists the awarded contracts to these companies (not Gilbert) for the tablets. All of these tablets were designed by architect Colonel Emmor Bradley Cope (July 23, 1834 - May 28, 1927). He designed pretty much every tablet for both the Union & Rebel armies, each one distinct, w/ several different varieties. He is buried in Evergreen Cemetery 
in Gettysburg, as well he should be as this park and most of the things seen here today were designed by him and as such, are his legacy. These monuments were erected just after the turn of the century during the first & beginning of the second decade of the 20th century. Each one has since been preserved or restored at least twice since the turn of the 21st century. The plaques & tablets were erected by the Gettysburg Park Commission (established by the War Dept.), after they took over the administration of the park from the Gettysburg Battlefield Memorial Association (whose funds had expired) on March 3, 1893, and whose stewardship was then transferred to the National Park Service in 1933) SOURCE The Gettysburg Park Commission is also referred to as the Gettysburg National Military Park Commission or the Gettysburg National Park Commission, to clear up any confusions, especially my own.
On October 1, 1898, the Gettysburg National Park Commission in a letter to the Secretary of War set gave recommendations for continuing the task of organizing & progressing the work of the Gettysburg National Military Park. Every November they wrote their annual report which outlined the work of the GNPC for that year. The following is an excerpt from that report relevant to this waymark. The link at the end of the paragraph will take you to the entire report. The method of marking the positions of troops on this field, as approved by the War Department, is to place the principal tablet or monument of each command at the position occupied by the command in the main line of battle, and to mark the several important positions subsequently reached by each command in the course of the battle by subordinate and ancillary tablets, with appropriate brief inscriptions giving interesting details and occurrences and noting the day and hour as nearly as possible. SOURCE
Most of the Commission reports have been digitized and can be found HERE. The initial 1893 report up to & including 1921 can be found here. 1922 to 1926 are missing & have yet to be discovered. The years 1927 to 1933 were discovered in 1996 and are also included. To my knowledge this is the most comprehensive list of documents that illustrated the development and formation of the park.
Information about these specific types of monuments:
DIVISION HEADQUARTERS MARKERS (For Union & Confederate Monuments)
Division headquarters are rectangular bronze tablets mounted on large, rectangular stones. Union headquarters have a corps or service branch symbol (like a cross, clover, star or crescent moon) as a separate bronze piece above the tablet (this one has the trefoil), while Confederate headquarters are labeled "C.S.A." on a separate bronze piece in an oval. There are 22 Union and 10 Confederate Division markers at Gettysburg. Both markers are of similar design and were all construed of Winnsboro (S.C.), granite. Each stands seven feet in height. SOURCE & SOURCE
The Gibbon's Division - US Division Tablet is a contributing feature to the Gettysburg Nat'l Military Park H.D. which is nationally significant under NR Criteria A, B, C & D. Areas of Significance: Military, Politics/Gov't, Landscape Architecture, Conservation, Archeology-Historic. Period of Significance: 1863-1938. The monument is designated as structure no. MN430.
From the Nomination Form:
1 of 23 Civil War US Division Markers in Park. Records movements & itinerary of 2nd Corps, 2nd Division commanded by Brig. General John Gibbon.
Short Physical Description:
Rough-hewn monolith, 4'2"x2'x7'H. Bronze inscription tablet, 3'8"x3'6-3/4", mounted on finished face of monolith. Polished, excised Trefoil Corps insignia centered above tablet.
Long Physical Description:
Located west side of Hancock Avenue near the Angle.
My Sources
1. NRHP Nomination Form
2. Stone Sentinels
3. Virtual Gettysburg
4. Draw the Sword
5. Historical Marker Database
6. Wikipedia