Fluorescence microscopy experiments using chromosome-paint probes reveal that chromosomes occupy discrete territories within the nucleus, but the precise nature of these territories is unclear. Transcriptional and RNA processing machinery can be observed at the surfaces of territories in the interchromosome domain. Indeed, some genes appear to reposition away from territories upon transcriptional activation. However, other studies suggest that not all active genes emanate from territories, and that transcriptional status is not related to nuclear position relative to the territory. The nuclear dynamics of the b-globin gene-cluster and how this relates to transcriptional regulation also remain unresolved. In human cells in which b-globin is transcriptionally inactive the gene can be observed towards the periphery of the chromosome territory and associated with repressive pericentric heterochromatin. In human erythroid cells expressing bglobin there is no evidence that the gene specifically moves away from the chromosome territory upon activation, but it no longer co-localises with pericentric heterochromatin. Experiments on the murine b-globin locus suggest that during early erythroid differentiation the Hbb-b1 is in a poised state at the periphery of the nucleus and away from the chromosome territory. Later in erythroid development, when the gene becomes active, it moves closer to the body chromosome and away from pericentromeric heterochromatin at the nuclear periphery. These results are contradicted by another study, which showed no extrusion of Hbb-b1 from the territory, either before or after transcriptional activation. Transcription does seem to play a role in b-globin spatial dynamics, as do enhancers. 4C data on the bglobin locus has yielded contradictory evidence regarding the importance of interchromosomal interactions. Here we present a novel method, which we call Completegenome 3C by vectorette amplification, that allows identification of physical associations of a genomic region. The method relies on the cloning and sequencing of 3C-mediated ligations to a specific sequence, and therefore is not biased towards a limited set of potential chromosomal interactions. Our data show the potential of this technique to assay genomic structure, and suggest that the b-globin gene may interact with other chromosomes more frequently during transcriptional activation. The relationship between structure and function in the nucleus has for a long time remained something of a mystery. This is in part due to a gap in the resolution in the techniques employed to study chromatin structure. Methods such as x-ray crystallography and electron microscopy allow high resolution analysis of chromatin structure. For example, recent work using electron spectroscopic imaging has revealed the molecular characteristics of transcription factories, without the use of PI-103 potentially artifactinducing heavy metals often used in staining. Much of what is known about nuclear structure at coarse resolution comes from light microscopy studies.