This paper describes a series of substantial pits of Mesolithic date, notable for their complex fill and recutting sequences, association with burnt and transformed materials, occasional linear arrangement, and connection to the observation of celestial phenomena. While likely tied into regular rounds of movement, it is argued they represent reserved and sacred places where special activities were undertaken which connected cosmic forces. Keywords Mesolithic, pits, alignments, cosmology 1. Mesolithic 'monuments' and landscape markers A remarkable record of monument building is associated with earliest (Neolithic) farming communities of Atlantic and Northern Europe, comprising a range of earthen and megalithic tombs, enclosures and menhirs (Scarre 2002; Bradley 2007; Cummings 2008). In contrast, ceremonial architecture belonging to post-glacial (Mesolithic) hunter-gatherers within these regions is slight, or, regionally, non-existent. Cummings and Harris rightly observe that 'the monuments constructed in the Neolithic are, without question, something very new' (2014:832). Notwithstanding these very real differences in the record for the two periods, evidence for Mesolithic monumentality has been posited, and deployed to shape narratives of the period which move beyond a long-standing focus on matters economic (eg Pollard 1990; Cummings 2000; Allen & Gardiner 2002; Blinkhorn & Little in press). At best, any definition of what constitutes a 'monument' or something 'monumental' will be loosely defined, but the terms evoke physical constructs, either humanly-made or natural, that possess size and durability, serve to commemorate or memorialise, and which may afford settings/spaces through which the living can intercede with ancestral and/or supernatural domains (Bradley 1993; Scarre 2011). Conneller (2011) cites examples of Mesolithic wooden landscape markers, middens and natural places as features that might be described as monuments. They can certainly be accommodated within broad definitions of monumentality that focus on scale, endurance and commemoration; though critique has been levelled at the interpretation of midden sites as monuments akin to later chambered tombs (eg Pollard 1990), not least because of their reading as such in relation to Neolithic frames of reference (Finlayson 2006; Warren 2007). Equally, one might see large circular houses of 9th to early 7th millennia cal BC date from northern Britain and Ireland, such as those at Howick, Northumberland (Waddington 2007), Echline Fields, in the Forth estuary (Robertson et al 2013), and Mount Sandel in Northern Ireland (Woodman 1985; Bayliss & Woodman 2009), as monumental in quality. Warren, for example, considers their extrahabitational role as enduring places which fostered common traditions, hospitality and connection (Warren 2015). Rather than being overly constrained by the monument label and its definitional boundaries and connotations, there is mileage in thinking through the different ways post-glacial hunter-gatherers transformed places through d...