In systems engineering, the interface is the part you design: the joint where two subsystems meet. PAZ’s concept panel on infrastructure systems design makes the case through Crossrail and Millau. At 3,020 m on the Titlis above Engelberg, the interface is a joint between two decades. One side is a steel antenna built in the mid-1980s for telecommunications by the former PTT. The other is a pair of glazed volumes Herzog & de Meuron added in a cross. The TITLIS Tower has been standing since 29 May 2026.

The essence is a decision not to demolish. According to Herzog & de Meuron’s project page, the 56 m steel tower was extended with two horizontal, fully glazed volumes in “far-reaching cantilevers”, arranged as a cross, plus four vertical circulation towers. Two of them are escape stairs and two hold lifts. The building now rises to about 75 m over 11 levels, with 3,950 m² of gross floor area. Of that, 1,490 m² sits below ground. The retail floor is in the lower volume and the restaurant in the upper one, with a 360° viewing platform on top. The entrance-level garage houses the piste groomers.

I know what it means to be kept. The concrete base is anchored deep into stable rock. Urdesignmag reports that this anchorage would be “extraordinarily difficult to replicate at altitude”. The same report says the filigree steel frame, built for alpine extremes, stayed structurally sound. The 1980s tunnel still gives a weather-protected route to the mountain station. That is three things no new building on that summit could easily buy: a foundation, a skeleton and an artery.

←TODAY: A 1980s PTT mast at 3,020 m now carries two glazed volumes and four circulation towers, open since 29 May 2026.
→3012: Zurich-3012 inventories every standing frame as stored labour before anyone draws a new line.
Fulcrum: The greenest structure on a summit is the one already bolted to the rock.

The credits matter, because a building like this has many authors. The partners are Jacques Herzog, Pierre de Meuron and Andreas Fries, who has been partner in charge since 2020. The client is TITLIS Bergbahnen. Schnetzer Puskas Ingenieure is the structural engineer, and Emmer Pfenninger Partner (EPPAG) planned the 5,020 m² façade. Caretta & Weidmann is executive architect from June 2025, following Architektur & Baumanagement AG. Behind them stand the crews who built in galvanised and stainless steel, concrete and glass, and the PTT engineers of the 1980s. Their names are rarely printed; their frame still does the work.

The architects describe it plainly. Pierre de Meuron: “The tower symbolizes a shift from purely functional structures towards a new generation of Alpine architecture.” Jacques Herzog: “The expressive steel structure was transformed into an iconic sculpture—a kind of signpost.” Andreas Fries: “The existing antenna tower was transformed into an iconic building with presence.”

Reuse has a trade-off, and it is a property of the method. Every new load has to find its way into a geometry you did not choose, so the 1980s grid sets the rules for the 2026 programme. Star Wars fans will recognise the instinct of Echo Base on Hoth: you build into what the ice already gives you, because hauling a new world up there is the harder war.

Building-sense: A structure like me, given new cantilevers, would feel the wind first. My old members would carry loads they were never sized for, so I would want strain gauges on the original nodes from day one. That way my memory of the 1980s and my body of 2026 report to the same nervous system.

Atelier: For a Swiss office holding a brief on an alpine station, a telecom mast or a disused industrial frame, the first deliverable is a condition record of what stands, not a massing study. PAZ has covered this thread before with TerraSense in Portugal, applying the HIM principle that what is not in the model does not exist for the next phase. The Monday move: create an “existing structure” layer in your Archicad or Rhino model, and tag every retained member with its source, age and survey status before any new geometry is drawn.

Hack: Check how thin the summit air is before you estimate the wind on a glazed cantilever. Air density falls with altitude, and so does dynamic pressure. Below, standard-atmosphere density sets the dynamic pressure, then sea level is compared with 3,020 m:

rho = lambda h: 1.225 * (1 - 2.25577e-5 * h) ** 4.2559  # kg/m³
q = lambda h, v: 0.5 * rho(h) * v**2                       # Pa
for h in (0, 3020):
    print(h, round(rho(h), 3), round(q(h, 40)))           # v = 40 m/s

You get about 0.91 kg/m³ and 726 Pa at the summit, against 980 Pa at sea level. A sanity check only: SIA 261 governs the design load, and ridge exposure usually outweighs the thinner air.

Walk your own portfolio and list one standing frame you would have demolished by default. Then price keeping it.