Warden Law Engine, on the Rainton and Seaham Railway, (SMR 2976). This was part of the Londonderry Railway, which closed in 1896 {2}. Two important colliery railways passed over Warden Law - the Hetton Railway going north and the Londonderry Railway going east. The two crossed between Copt Hill and Warden Law.
At the highest point on the Londonderry Railway stands the Warden Law Engine. The trackbed can be followed in the area and the engine house is virtually complete. The extant buildings comprise the original stone engine house with brick extensions which were built to form a locomotive shed. The original engine house probably dates from circa 1830 and so is perhaps the oldest colliery railway building in the county.
The importance of the Londonderry Railway is well recorded and gives this survival added significance. The additions and alterations to create a locomotive shed are from the mid-19th century. It has been suggested that locomotive working on this section of the line began as early as 1845, though evidence is lacking. By 1890 locomotives were being kept at Rainton and one at Warden Law in the converted engine house.
The brick extension features some fine railway architecture. The whole is partially disused and partially used as a hen house. A small adjacent brick building probably dates from the same period as the locomotive shed and has some railway function, although its use, is as yet unclear. These buildings, particularly the stone engine house and the added locomotive shed should be listed for historical reasons {3}.
Recorded in 2017 ahead of conversion to a tea room. The report noted that the structure had degraded significantly since its recording in 1994. The roof had been replaced more than once, and the wall heads are all but gone. The central wall within the engine house has gone, barring a small section at its western end, and the entire north wall, southeastern walls and most of the northwest corner have had to be replaced.

The Rainton and Seaham Railway. The western end was where it split into the Adventure and Framwellgate branches, (SMR 3195 and SMR 3200 respectively), at Nicholson's Pit, (SMR 3201). The line was built by the Marquis of Londonderry, it opened in 1831 and was worked entirely by inclines. The line closed in 1896, but the section from near Copt Hill to the North Hetton Branch, along with that branch, was taken over by the Hetton Coal Company and worked until 1917. At Rainton Bridge, the line used to cross the Sunderland to Durham toll road at level crossing gates. The gates were operated by a crossing man who had a cabin beside the well on the Houghton side of Rainton Bridge. However by 1917 an increase in road traffic meant the gates were nuisance and so a bridge was built by Mr Balfour of Houghton-le-Spring. NZ 3375 4859. In 2019 the railway embankment and drainage ditch was identified during an evaluation located at land at Hetton road by Pre-construct archaeology.

Reservoir.

Quarries, marked as Old on the 1st edition OS mapping, so was out of use by 1856.

The Flat Engine with a reservoir on the Hetton Company's Railway, (SMR 2848).

Warden Law Windmill, marked as ruinous on the 1st edition OS mapping of 1856 survey date.

Quarry, marked as Old on the 1st edition OS mapping, so was out of use by 1856.

Two Reservoirs.

Warden Law Engine, on the Hetton Company's Railway (SMR 2848). This was a Beam Engine, built in 1836 and has been "preserved for inclusion in the Regional Museum" {2}.

Reservoir.