Lunca de Jos is situated 39 km far from Miercurea-Ciuc along National Road 12A. It consolidated as a commune about 1810. Spreading from Valea Boros as far as the Trotus bridge under Valea Rece, Lunca de Jos has almost grown together with Lunca de Sus. The settlement consists of scattered alpine colonies. Until 1782, it used to be affiliated to Nicolesti; since 1795 it has already belonged to the Ghimes parish. The village separated from Lunca de Sus in the early 1900s, after the latter had already become independent. The main occupations here were shepherding and trade. Following the railway-building, a wood-mill was made in the settlement; the board factory still works. The commune has 5,317 inhabitants, out of which 5,250 Magyars. The population of Lunca de Jos village itself is of 1,175 (23 Romanians, 1,152 Magyars). The railway station of Lunca de Jos is situated in the vicinity of the place where the Ciuc Stream flows into the Trotus. Its excellent bath in Valea Intunecoasa is used in the treatment of rheumathic diseases.
The small settlements come after one another in the Trotus Valley.
- Valea Boroş (Borospataka) or (Boros). In its valley opening to the east (right) flows the Boros Stream of which upper flow takes the name Hidegkúti Valley. It springs from the Hidegkút near Apahavas (1,330 m). The right parts of the valley are steep, while the left ones are gently sloping. It is inhabited by 429 people, all Magyars.
- Valea Întunecoasă (Setétpataka) or (Sötétpatak). It can be approached along the no. 10 local road from National Road 12A (1.4 km). The village is situated 33 km far from Miercurea-Ciuc, at 900 m altitude. The Nascalat Peak (1,566 m) rises in its vicinity. In the valley opening to the west (left) a small spa was made on the turn of the century. It has three bicarbonic-earthy, carbonic mineral water springs, indicated against the diseases of the vascular system as well as rheumathism. The water of two springs are used by the hot bath, the third is used as drinking water. There are 11 bathtubs at the small spa. Its further development depends on the results of the hydrogeological research. Valea Întunecoasă has 240 inhabitants, except one person all are Magyars. The settlement was first mentioned in 1797.
- Valea Capelei (Kápolnapataka) or (Kápolna). It is a short valley section opening to the right of National Road 12A, after the railroad crossing. Valea Capelei has 319 inhabitants, all Magyars. The Tarcau railway station is in its vicinity; this is the highest point of the country. The Roman Catholic church of the small settlement was built in 1853.
- Valea lui Antaloc (Antalokpataka) or (Antalok). It is situated to the west (left) of National Road 12A. Its 254 inhabitants are all Magyars.
At the end of Lunca de Jos, passing the railway, a long valley opens to the left (along the 127A county road). This is the Valea Rece spreading deeply under the long crest of the Nascalat. The Rece Stream is the longest and most aboundant branch of the upper section of the Trotus. Several small scattered settlements are to be found along the 127A county road running up in Valea Rece:
- Bánpataka or Bándpataka. Bánpataka is the first stream valley left to the National Road (12A). This little valley has deepened into the Carpathian sandstone. The stream flows in the foreground of the Bán Mountain (1,129 m) and the Lápos (1,349 m). The settlement has a small church in the mouth of the valley. It borders on Bacau county in the east.
- Kovaş (Kováspataka, on the map: Kovás). A small valley opens westwards (leftwards), at a 2.5 km distance from the railway crossing, at 814 m altitude. The houses of the settlement are to be found here in the valley. Opposite to it, the Bándi Stream flows into the Rece Stream.
- Şălămaş (Szalamáspataka) or Szalomás (on the map: Szalamás, Szalomás). This small valley also opens from the direction of the Kondra cross to Valea Rece. It is bordered by high hillsides in the south and north. The Cokán Stream springs from the north. Coal-mining can be noticed here; at the end of the 19th century coal was extracted in 6 tunnels on a 141 m length.
- Valea Rece (Hidegség). Valea Rece can be approached along the 127A county road (main road) (9 km). It is a road-settlement with 2,214 inhabitants (10 Romanians, 2,184 Magyars and 20 Gypsies) in 1992. The name of the village was already mentioned in 1750. The Roman Catholic wooden chapel of the settlement was built at the end of the 19th century. Four more streams flow into the valley.
- Iavardi (Jávárdipataka). The Iavardi Valley is one of the most beautiful ones of the Ghimes country. The Roman Catholic Saint Anthony wooden chapel (built in the 19th century), listed building of Harghita county (1992), stands on its area. From the lower-Triassic limestones of the Iavardi Crest (1,445 m) the locals used to burn lime. There is a 6-8 m high waterfall named "Zógó" on the Iavardi Stream.
- Poiana Fagului (Bükkhavaspataka) or (Bükkhavas). It is situated 10 km far from National Road 12A. In 1992, Poiana Fagului had 70 inhabitants, with the exception of 4 Romanians, all were Magyars. In 1898, it was registered as other inhabited place of Lunca de Jos, with the name Bükkhavaspataka. It has four streams.
- Baraţcoş (Barackospataka) or (Barackos). This settlement makes up the "end" of Valea Rece. Its border is the 1,340 m high Baraţcoş Mountain in the north and the Orogyik in the south. In 1992, it had 255 inhabitants, all Magyars except 3 Romanians. There is a mineral water spring and a small spa in its side-valley on the right, in the Muhos Stream.
- Puntea Lupului (Farkaspalló). In 1913, the colony belonged to Danesti. It lies 18.5 km far from National Road 12, 57 km far from Miercurea-Ciuc. Out of its 161 inhabitants 6 are Romanians, all the others being Magyars. The no. 127A county road leads to Neamţ county through the watershed, then it reaches National Road 12C at Bicaz-Chei. Barátostelep belongs to Puntea Lupului.
- Trei Fântăni (Háromkút). Trei Fântăni is a small settlement between the Hasmasu Negru (1,792 m) and the Határkő (1,218 m) along the upper flow of the Bicazu Mic Stream. It lies to the west of Puntea Lupului. Administratively, today it belongs to Dămuc settlement of Neamţ county. Next to the Tarcau plateu there is a "triple" karst spring.
Returning to National Road 12A from Valea Rece, the last settlement consisting of scattered farmsteads of Lunca de Jos in the Trotus Valley is Valea Mare.
Other places of interest in Lunca de Jos: at no. 822: peasant economy (house, kitchen, barn from the beginning of the 19th century). The fuller of Káruly Péter Kicsi (no. 850): from the beginning of the 19th century). Péter Csillag (no. 1041): a watermill and a locksmith's workshop (from the 19th century). It appears on the List of Monuments of Harghita county (1992).
- Valea Mare (Nagypatak). Valea Mare is a valley opening to the right (south) of National Road 12A, beyond the railway crossing (Tarcău). It is a place with rich pastures and grasslands. There used to be a small wood-mill and a mineral water spring in its valley.
In the north of Lunca de Jos commune, at the foot of the Orodic (1,177 m) is the border of Harghita county (59 km far from Miercurea-Ciuc along National Road 12). The old border was actually marked at the Buha- or Border Stream. Crossing the Trotus bridge we already reached Bacău county.