A modular data center comprising: a plurality of unit structures arranged generally parallel to one another; and a plurality of supports for supporting the unit structures elevationally above a floor, and wherein adjacent ones of the unit structures form hot aisles therebetween through which hot air generated from data center components may be channeled; each said unit structure forming an elongated structure having: a frame structure; a roof panel supported by the frame structure; a ceiling panel spaced apart from the roof panel for defining a volume through which the hot air from one of the hot aisles may be received and channeled; the roof panel helping to form a cold aisle between adjacent rows of data center components disposed below the unit structure, the cold aisle being configured for channeling cold air between the data center components; the modular data center further comprising: a plurality of bridging ceiling panels disposed between adjacent ceiling panels of adjacently positioned ones of the unit structures, to assist in forming the hot aisles; wherein the data center components are positioned under each of the unit structures in two rows facing one another to help form the cold aisle, and wherein one said row of each of the two rows of data center components from adjacent ones of the unit structures helps to form one of the hot aisles therebetween. a plurality of unit structures arranged generally parallel to one another; and a plurality of supports for supporting the unit structures elevationally above a floor, and wherein adjacent ones of the unit structures form hot aisles therebetween through which hot air generated from data center components may be channeled; each said unit structure forming an elongated structure having: a frame structure; a roof panel supported by the frame structure; a ceiling panel spaced apart from the roof panel for defining a volume through which the hot air from one of the hot aisles may be received and channeled; the roof panel helping to form a cold aisle between adjacent rows of data center components disposed below the unit structure, the cold aisle being configured for channeling cold air between the data center components; a frame structure; a roof panel supported by the frame structure; a ceiling panel spaced apart from the roof panel for defining a volume through which the hot air from one of the hot aisles may be received and channeled; the roof panel helping to form a cold aisle between adjacent rows of data center components disposed below the unit structure, the cold aisle being configured for channeling cold air between the data center components; the modular data center further comprising: a plurality of bridging ceiling panels disposed between adjacent ceiling panels of adjacently positioned ones of the unit structures, to assist in forming the hot aisles; wherein the data center components are positioned under each of the unit structures in two rows facing one another to help form the cold aisle, a plurality of bridging ceiling panels disposed between adjacent ceiling panels of adjacently positioned ones of the unit structures, to assist in forming the hot aisles; wherein the data center components are positioned under each of the unit structures in two rows facing one another to help form the cold aisle, and wherein one said row of each of the two rows of data center components from adjacent ones of the unit structures helps to form one of the hot aisles therebetween.