The 6th Maine Infantry served as a member of Russell’s Brigade in Wright’s Division of the Sixth Corps, Army of the Potomac, a Fighting 300 Regiment. The 6th Maine Infantry was organized in Portland, Maine and mustered in for a three year enlistment on July 15, 1861. The 6th Maine Infantry mustered out of service August 15, 1864. Veterans and recruits were transferred to the 7th Maine Infantry and soon consolidated to become the 1st Maine Veteran Infantry. While at Gettysburg, the regiment was commanded by Colonel Hiram Burnham (1813 - Sep. 29, 1864). On September 29, 1864, commanding his corps at the Battle of Fort Harrison near Richmond, Virginia, he was killed in action. General Burnham was buried in Pine Grove Cemetery in Cherryfield. The U.S. Army renamed the captured Fort Harrison as Fort Burnham in his honor. Under his command, the 6th brought 439 men to the Gettysburg Battlefield suffering no losses. All totaled, the regiment lost a total of 255 men during service; 12 officers and 141 enlisted men killed or mortally wounded, 2 officers and 100 enlisted men died of disease.
The 6th Maine Infantry Monument is located 485 feet southeast of the intersection of Taneytown Road (Route 134) and Wright/Howe Avenues. The monument is on Howe Avenue on the left or north side of the road it traveling southeast toward the cul-de-sac. As a point of reference, at the intersection, a left turn is Wright Avenue and a right turn is Howe Avenue, even though they are the same road, if traveling north. At the beginning of Howe Avenue, on the left is the 
Albion Howe's Headquarters Marker (MN398), then the 119th Pennsylvania Infantry Monument (MN377-B) and then the Battery C, 1st New York - US Battery Marker (557-A). All the monument are equidistant apart, more or less. 
Parking is available at the end of Howe Avenue in the cul-de-sac. There is no other room to park on this road as there are no shoulders and it accommodates two way traffic. I visited this site on Monday, July 1, 2013 on the 150th anniversary of the Battle of Gettysburg @ 1:07 PM, EDT & @ an altitude of 463 feet, ASL. As always, I used my trusty and oft abused Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
The Draw the Sword site helped out by the NPS narrative and the SIRIS site offers the following description: Columnic shaft stands on a rough-hewn base. The second course of the shaft is fluted. At the top is a four-sided Greek cross, the 6th Corps insignia. Monument is a three-course granite shaft topped with a Greek Cross on four sides and set on a 5.2 foot square rough hewn base. The second course of the shaft is fluted. It has incised inscriptions on the east and south sides. Overall height is 21.6 feet.
The 6th Maine Infantry Monument was dedicated on October 3, 1889 by the State of Maine. The monument is composed of red and white granite and has the following dimensions:The sculpture is approximately 21 feet 6 inches and the base is approximately 2 feet 9 inches x 5 feet 2 inches². The sculpture was fabricated by the Hallowell Granite Company. The are brief inscription on the front and back of the monument, all of which read:
(Front):6th Maine
Infantry
3rd Brigde
1st Div.
6th Corps.
(Left Side):Held this position
July 3, 1863.
in afternoon moved
to support of centre.
Then to Big Round Top.
The 6th Maine Infantry Monument is a contributing feature to the Gettysburg National Military Park Historic District which is nationally significant under NR Criteria A, B, C & D. Areas of Significance: Military, Politics/Government, Landscape Architecture, Conservation, Archeology-Historic. Period of Significance: 1863-1938. The original National Register Nomination was approved by the Keeper March 19, 1975. An update to this nomination was approved by the Keeper on January 23, 2004. The monument is identified as structure number MN378.
From the Nomination Form:
1 of 15 Civil War mns in Park of the GBMA Era (1863 - 1895) honoring commands in Gettysburg Campaign. Mark location held by 6th Miane Infantry on July 3, 1863. Located on north side of Howe Ave, near its center.
Short Physical Description:
Rough-hewn base, 5'2" sq, shaft, 2'9". 3-course shaft, fluted on 2nd part. Topped w/ 4-side Greek cross. Incised inscriptions on E & S faces. All 21'6" H.
Long Physical Description:
Monument is a three-course granite shaft topped with a Greek Cross on four sides and set on a 5.2 foot square rough hewn base. The second course of the shaft is fluted. It has incised inscriptions on the east and south sides. Overall height is 21.6 feet. Located on the north side of Howe Avenue.
My Sources
1.
NRHP Nomination Form
2.
SIRIS
3.
Virtual Gettysburg
5.
Draw the Sword
6.
Historical Marker Database
7.
Wikipedia