Site · Multiple connections
Iron Mountain LON-1 London Data Center
Operating / Stabilized · Slough, England, United Kingdom
Same locality: SloughShared participant: Iron Mountain Data Centers
All records
Data center siteSite record
Iron Mountain LON-3 London Data Center
Slough, England, United KingdomUnder construction
Capacity
25 MW
Planned critical IT
Lead participant
Iron Mountain Data Centers
Developer
Last updated
Aug 28, 2026
Most recent public record update
About Iron Mountain LON-3 London Data Center
LON-3 is the third Iron Mountain building at Slough and remains under construction. Its 25 MW is a future facility boundary; Q2 2026 reporting gives Q1 2027 expected completion, no pre-leased MW and $391.9 million total expected investment. None of those values is represented as operating capacity. Customer utilization, private contract terms and unreported project financing remain outside the verified public record.
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Projects sharing a market, utility, or organization.
Site · Shared context
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Operating / Stabilized · Slough, England, United Kingdom
Same locality: Slough
Site · Shared context
CyrusOne LON3 Slough Data Center
Operating / Stabilized · Slough, England, United Kingdom
Same locality: Slough
Site · Shared context
CyrusOne LON4 Slough Data Center
Operating / Stabilized · Slough, England, United Kingdom
Same locality: Slough
Capacity
Planned critical ITOperating capacity—An operating IT-capacity figure has not been publicly disclosed.
It Load25 MWDesign · Iron Mountain LON-3 London Data Center
Future Potential25 MWDesign · Iron Mountain LON-3 London Data Center
Development
1 phases · 2 milestonesDevelopment, permitting and phased deliveryUnder Construction
LON-3 is the third Iron Mountain building at Slough and remains under construction. Its 25 MW is a future facility boundary; Q2 2026 reporting gives Q1 2027 expected completion, no pre-leased MW and $391.9 million total expected investment. None of those values is represented as operating capacity. Customer utilization, private contract terms and unreported project financing remain outside the verified public record.
Aug 29, 2026
Project-specific evidence refreshed and reconciled
CompletedMar 31, 2027
LON-3 future phases expected to complete
ForecastInfrastructure
Electric GridPlanned Or Represented
25 MW
25 MW is a future LON-3 build boundary. Q2 2026 reporting gives Q1 2027 expected completion and shows no pre-leased MW; it is not operating capacity.
FiberPlanned Or Represented
Liquid-cooling-capable facility with redundant power and cooling, dark fiber, LINX access and GPU-ready configurations.
Cooling SystemPlanned Or Represented
Cooling and resilience architecture is described at facility or campus level; instantaneous draw and tenant utilization remain undisclosed.
Project map
0 of 1 project point mappedInfrastructure facts
3
Mapped records
1
Capacity figures
1
No map point available
Power & interconnection: 1Cooling & water: 1Fiber & connectivity: 1
Facts & sources
Published claims and their source links.
Location ContextLON-3 | Slough | England | GBActual
LON-3 | Slough | England | GB
Lifecycle StatusConstructionActual
Construction
Reported Capacity25 MWDesign
25 MW
Capacity BasisIron Mountain publishes 25 MW for the LON-3 facility record boundary.Actual
Iron Mountain publishes 25 MW for the LON-3 facility record boundary.
Location ContextLON-3 | Slough | England | GBActual
LON-3 | Slough | England | GB
Lifecycle StatusConstructionActual
Construction
Reported Capacity25 MWDesign
25 MW
Capacity Basis25 MW is a future LON-3 build boundary. Q2 2026 reporting gives Q1 2027 expected completion and shows no pre leased MW; it is not operating capacity.Actual
25 MW is a future LON-3 build boundary. Q2 2026 reporting gives Q1 2027 expected completion and shows no pre leased MW; it is not operating capacity.
Operator Or DeveloperIron Mountain Data CentersActual
Iron Mountain Data Centers
Project LocationSlough, England, GBActual
Slough, England, GB
Current LifecycleUnder developmentActual
Under development
Capacity ClassificationFuture potentialActual
Future potential
Capacity Basis25 MW is a future LON-3 build boundary. Q2 2026 reporting gives Q1 2027 expected completion and shows no pre leased MW; it is not operating capacity.Actual
25 MW is a future LON-3 build boundary. Q2 2026 reporting gives Q1 2027 expected completion and shows no pre leased MW; it is not operating capacity.
Customer UtilizationNot publicly disclosedActual
Not publicly disclosed
Source Refresh Date2026-08-29Actual
2026-08-29
Renewable Energy MatchingOperator states 100% matched renewable energy where applicableActual
Operator states 100% matched renewable energy where applicable
Sec Capacity ComparisonQ2 2026 leaseable and development schedules reviewedActual
Q2 2026 leaseable and development schedules reviewed
Expected CompletionQ1 2027Forecast
Q1 2027
Preleased Percent0 percentActual
0 percent
Total Expected Investment$391,900,000Transaction Scope
$391,900,000