Rotunda or Grotto is a Grade II listed building in the Gwynedd local planning authority area, Wales. First listed on 14 January 1971. Lookout structure.
Rotunda or Grotto
- WRENN ID
- turning-pillar-wagtail
- Grade
- II
- Local Planning Authority
- Gwynedd
- Constituency
- Dwyfor Meirionnydd MP: Liz Saville Roberts (PC)
- Country
- Wales
- Date first listed
- 14 January 1971
- Type
- Lookout structure
- Address
- Rotunda or Grotto, Portmeirion, Penrhyndeudraeth
- OS grid reference
- SH 590 371
- Coordinates
- 52.9134, -4.09729
- Source
- Cadw listing
Description
The Rotunda, also known as the Grotto, is a rounded structure built as a lookout platform with a grotto below. It is made of rendered brick and concrete, featuring low slab-coped parapet walls. The building has a semi-circular, single-storey flat-topped drum that is built into the hillside, with a viewing platform and parapet at the roof level. In the center of the concrete platform stands a cast iron fluted column topped with a metal astrolabe. The lower grotto area has arched entrances and five rectangular barred openings with outward splays.
Inside, the walls and ceiling are lined with scallop shells and conches embedded in concrete. A slate bench runs along the entire length of the hillside. In the center of the grotto is a dolphin fountain made of painted wood, and opposite it are six rectangular niches positioned between the window openings.
Local climate
Rotunda or Grotto sits in one of the wettest parts of the UK, with an average of 1,490 mm of rain a year. This makes it wetter than 98% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 97% of listed buildings.
It experiences an average of 32 freeze-thaw cycles a year, fewer than 60% of listed buildings. Of these, 15 follow at least 1 mm of rain in the preceding 48 hours. Average temperatures at this location have risen by 0.3°C per decade since 1991.
Averages for 1991–2020; temperature trend 1991–2025. Figures describe the wider area (a grid cell of roughly 10 km), not the individual site. Contains modified Copernicus Climate Change Service information 2026.
More on this building
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- No EPC on record for this property
- No sale records on file
- No related consent applications matched
- Detailed attributes — period, style, materials, features
- Flood risk assessment
- Radon risk assessment
- Weather exposure and heating demand — rain and frost month by month and year by year, wind direction, solar and humidity
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