Observatory at Bryn Bras Castle is a Grade II listed building in the Gwynedd local planning authority area, Wales. First listed on 27 August 1999. Observatory.

Observatory at Bryn Bras Castle

WRENN ID
tangled-tallow-fog
Grade
II
Local Planning Authority
Gwynedd
Constituency
Dwyfor Meirionnydd MP: Liz Saville Roberts (PC)
Country
Wales
Date first listed
27 August 1999
Type
Observatory
Address
Observatory at Bryn Bras Castle, Bwlch, Llanrug
OS grid reference
SH 545 625
Coordinates
53.14051, -4.17641
Source
Cadw listing

Also on this page: flood risk · radon risk · weather exposure · detailed attributes ↓

Description

The observatory at Bryn Bras Castle is a circular tower with a somewhat squat appearance. It is constructed from rendered rubblestone, sitting on a simple plinth, and features a rendered brick parapet with a horizontal railing on the flat roof. The tower has round-headed windows that are fitted with iron bars but lack glazing, and the entrance is located on the southeast side, accessible by a short flight of steps. Below the parapet, there is a stone corbel table.

While the interior was not accessible during the survey in February 1999, it is noted to contain one ground-floor room with a staircase that leads to a viewing platform on the roof.

Local climate

Observatory at Bryn Bras Castle sits in one of the wettest parts of the UK, with an average of 1,380 mm of rain a year. This makes it wetter than 97% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 98% of listed buildings.

It experiences an average of 25 freeze-thaw cycles a year, fewer than 73% of listed buildings. Of these, 12 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.

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