• Main Interior Floors: The primary focus was on the interior sacred spaces, including the celestial room, sealing rooms, and assembly halls. These areas received restoration efforts to preserve original murals, stained-glass windows, ornate woodwork, and fixtures from 1893.
• Mezzanine Levels and Corridors: These connecting and support spaces were upgraded with improved lighting, fire safety, and accessibility features while preserving the original architectural details.
• Underground Levels & Expansion Spaces: New chambers, including additional sealing rooms (expanded from 13 to 22) and a second baptistry, were constructed beneath the existing structure as part of the expansion project. These are new spaces, not original floors.
• Roof & Spires: Although not floors, the roof and the iconic spires underwent structural reinforcement and repairs.

What Was Preserved:

• Original murals and religious art that were carefully documented, removed temporarily during seismic work, then restored and reinstalled.
• Architectural features such as stained-glass windows, moldings, and wood finishes from the 1893 construction.
• Key decorative elements like the cast-iron oxen at the baptismal font and historic stone staircases.
• Interior finishes reflecting Victorian-era craftsmanship, including detailed woodwork and historic fixtures.

What Was Removed (and not intended to return):

• Murals and artwork were temporarily removed for structural reinforcement but are planned for reinstallation after restoration.
• Outdated mechanical, electrical, and plumbing systems that no longer meet current standards were replaced—these are modern upgrades, not historic features.
• Non-historic or incompatible interior fixtures or finishes that conflicted with preservation standards.

All the Modern Technology Added:

• Seismic Safety Systems: Nearly 100 base isolators allowing the building to sway safely during earthquakes.
• Structural Reinforcements: Steel reinforcement and foundation improvements to ensure long-term durability.
• HVAC (Heating, Ventilation, Air Conditioning): Modern, energy-efficient systems with climate controls to ensure comfortable and stable interior environments.
• Lighting: LED lighting with smart controls for energy efficiency and enhanced illumination of interior spaces.
• Electrical & Mechanical System Overhauls: New wiring, electrical panels, and high-efficiency HVAC components that support energy savings and sustainability.
• Fire Safety & Security: Advanced fire detection, alarm systems, and surveillance to meet current safety codes.
• Accessibility Features: Modern elevators, ramps, and signage to meet ADA standards.
• Digital Audio-Visual Equipment: Upgraded sound and projection systems for presentations and events, though the traditional worship experience remains central.

This meticulous renovation balanced preserving the historic aesthetic and spiritual significance with state-of-the-art safety and comfort upgrades.