Plant building, plant, and combined-cycle plant

A plant building comprising:

• a building body that has a first installation region where a first rotary machine having a first rotary shaft rotatable about a first axis is installed and a second installation region where a second rotary machine having a second rotary shaft rotatable about a second axis, which is disposed so as to be parallel to the first axis and to be spaced apart from the first axis in a horizontal direction, is installed;
• a first overhead crane that is disposed in the building body and is capable of traveling above the first installation region in the horizontal direction orthogonal to the first rotary shaft;
• a second overhead crane that is disposed at a position lower than the first overhead crane in the building body and is capable of traveling above the second installation region in the horizontal direction orthogonal to the second rotary shaft;
• a first ceiling provided above the first overhead crane;
• and
• a second ceiling provided above the second overhead crane at a position lower than the first ceiling,
• wherein the first ceiling has a pair of first traveling rails which extends in the horizontal direction orthogonal to the first rotary shaft in a state of being parallel to each other, and
• the second ceiling has a pair of second traveling rails which extends in the horizontal direction orthogonal to the second rotary shaft in a state of being parallel to each other.