The monument to the 154th New York Volunteers is on the northeast side of Gettysburg on Coster Avenue, one of the few monuments in the town itself, (39.835133° N, 77.227571° W; Google map) It was dedicated in 1890 by the State of New York.
The 154th New York was commanded at the Battle of Gettysburg by Lieutenant Colonel Daniel B. Allen. It brought 274 men to the field.
A monument to Amos Humiston is about 400 yards south on Stratton Street. Humiston was an enlisted man from the 154th who was mortally wounded on July 1. His unidentified body was found after the battle clutching a photograph of his small children. This led to a nationwide search which identified his wife and children.
The 154th New York is also honored by a monument on the Chancellorsville battlefield.
The 154th New York was attached to the 1st Brigade, 2nd Division, 11th Corps
From the front of the monument:
154th New York Infantry,
1st Brigade, 2nd Division 11th Corps,
July 1, 1863
From the left side:
July 2nd and 3rd
on East Cemetery Hill.
From the rear:
Killed, men 1.
Wounded, officers 1, men 20.
Captured or missing,
Officers 9, men 169,
From the right side:
Died while prisoners, 42
See more on the 154th New York Volunteer Infantry Regiment in the Civil War