During the 15th and 16th century Snowdonia was wild, lawless and sparsely populated. The crude houses with turf roofs and earthen floors provided little more than basic shelter for the inhabitants. According to legend "Ty Hyll", the "Ugly House", was built in 1475 by two outlaw brothers. It was a "Ty Un Nos" or "House of the Night". It was said that he who could build a rough house overnight and have smoke coming from the chimney by dawn could claim the land freehold. The boundary of his little estate could be further extended by the distance that he could throw his axe from the four corners of his new dwelling. A lonely secluded spot would be chosen, all materials assembled, friends summoned to help and at sunset the work commenced. It is suspected that some poetic licence was allowed and it was sufficient if the walls were roughly built and smoke was coming out of a hastily improvised chimney.

Life in those days was hard, primitive and, by our standards, unbelievably uncomfortable. Outlaws and their associates were at the bottom rung of the economic ladder. The one room would often be shared with the family pig or even a cow, a few hens might be in another comer.They would be almost totally dependent on their own resources for food with the occasional walk over the mountains to Llanrwst on Fair Day to buy basic necessities that they could not produce themselves. Furniture would be virtually non-existent, a roughly made table, a couple of stools and a bench or two, some straw or bracken pallets and sacks in a comer would act as bedding. Until the beginning of the nineteenth century the little dark house hidden in dense woodland had a sinister reputation. it provided an isolated hide-out for thieves and vagabonds. It gave them easy access across the ford and over the stepping stones to the road from Betws-y-Coed to Bangor on the other side of the river, little more than a cart-track in those days. The occasional coach and lonely traveller were waylaid, relieved of their valuables and the thieves disappeared into the thick woods.

Telford, Ty Hyll and the A5

In 1815 Thomas Telford, the great builder of Bridges and Roads built the Waterloo Bridge at Betws-y-Coed as part of his plan to take the London to Holyhead Road through the Ogwen valley instead of the long detour by Chester. In order to avoid constant flooding, Telford decided to abandon the old road between the Swallow Falls and Capel Curig and cross the River Llugwy opposite Ty Hyll. His contractor undertook to build the Bridge by the 21st November 1819 at a cost of £2,957.15s. Some of the men who worked on the road and bridge found the primitive cottage abandoned as it no longer provided the necessary seclusion for the nefarious activities of the previous occupants. The road navvies in Telford’s day worked long hours and lived in rough conditions. No doubt Ty Hyll was infinitely preferable to the often inadequate tents provided by the contractors. They probably did some rough repairs, mended the windows, patched the roof and kept themselves warm and dry. They may have built the attic specified in its Grade II listing "Single room with loft above". Telford visited the Bridge several times during construction and there is no doubt that he took an interest in Ty Hyll where some of his men lodged. In 1821 Ty Hyll Bridge was finished and the gangs moved on to Capel Curig and Ogwen. When it became too far for the men to walk back to their sanctuary, the cottage was again abandoned. it might have been used by the occasional shepherd or drover as a shelter for a night when driving sheep and cattle to the markets. It does not appear in the great Census of 1841 when every habitable residence was recorded. This may have been because it was a "Ty Un Nos" and therefore claimed squatters rights. But in 1853 it did receive an honourable mention in a "Tourist Guide to North Wales". The author wrote, "Walking from Capel Curig to Betws-y-Coed and near to the two mile stone is one of the most picturesque cottages imaginable placed on the side of the hill above the bridge that crosses the River Llugwy and gives additional beauty to this romantic dell."