Flags of Austria-Hungary

Austria-Hungary (often referred to as the Austro-Hungarian Empire) did not have a common flag (a "national flag" could not exist since the Dual Monarchy consisted of two sovereign states). However, the flag of the ruling Habsburg Dynasty was sometimes used as a "de facto" national flag and a common civil ensign was introduced in 1869 for civilian vessels. Until 1918, the k.u.k. War Fleet continued to carry the Austrian ensign it had used since 1786; and the regiments of the k.u.k. Army carried the double-eagle banners they had used before 1867, as they had a long history in many cases. New ensigns created in 1915 were not implemented due to the ongoing war. At state functions, the Austrian black-yellow and the Hungarian red-white-green tricolor were used.
Austria was represented by the black-yellow flag. The Hungarian half of the state, on the other hand, legally had no flag of its own. According to the Croatian–Hungarian Settlement (art. 62 and 63), in all joint Croatian and Hungarian affairs, symbols of both Croatia and Hungary respectively had to be used. For instance, whenever the joint Hungarian-Croatian Parliament held its session in Budapest, both the Croatian and Hungarian flags were hoisted on the parliament building in Budapest. In Vienna, in front of Schönbrunn Palace, the black and yellow flag was flown for Cisleithania (Austrian half), while both Croatian and Hungarian flags were flown for Transleithania (Hungarian half). Hungary proper used a red-white-green tricolor defaced with the Hungarian coat of arms, sometimes used to represent the entirety of the Lands of the Hungarian Crown. The "double" civil ensign, as a symbol of "corporate identity", was also used as the consular flag, as decreed on 18 February 1869. It came into use on 1 August 1869. Legations, however, flew the black-and-yellow flag of Austria alongside the red-white-green flag of Hungary, while embassies flew the two national flags alongside the imperial standard.
Coat of arms.
The double-headed eagle of the House of Habsburg was used as the coat of arms of the common institutions of Austria-Hungary between 1867 and 1915. In 1915, a new one was introduced, which combined the coat of arms of the two-halves of the Dual Monarchy and that of the dynasty.
Additionally, each of the two parts of Austria-Hungary had its own coat of arms.

Country park.
Following the Countryside Act 1968, the estate was sold in 1969 by William Stanhope, 11th Earl of Harrington to Derbyshire County Council. By The Countryside Act proposed the creation of "country parks", "for the enjoyment of the countryside by the public". The council opened the estate to the public in 1970 and have operated it since then, as Elvaston Castle Country Park. In 1969, Elvaston was also used as a location for Ken Russell's film adaptation of the D.H. Lawrence novel "Women in Love".
Today.
The deterioration of the castle and estate which started after World War II continued until the 1970s. Although restoration work was carried out and the gardens and park brought back into good heart,the operating costs were significant. With dwindling public funds available, and priorities elsewhere by 1990 the castle was considered unsafe and was closed to visitors. In 2000, the council estimated the country park’s running costs were £500,000 a year, and that they were facing a backlog of restoration work which would cost £3,000,000. 
In 2006, Derbyshire County Council commissioned a report, which estimated the castle and estate required at least £6.1 million of work and materials in essential repairs. Whilst development partners were interested in the Castle, a combination of public opposition and difficulty creating a plan which would achieve a suitable balance of development and access meat that these plans fell through. 
In 2013 The County Council asked The National Trust for help to create a future vision for the estate. This led, in 2015, to the County Council recruiting a Project Development Board to help it shape a future for the Estate as a charitable enterprise, further developing the Masterplan and exploring options for a sustainable future. This led to the formation of a totally independent board of Trustees in 2017 - The Elvaston Castle and Gardens Trust - and to the beginning of a new era for the estate.
Hauntings.
The castle is thought by some to be haunted: various professional investigations have been conducted in the castle, with phenomena being reported including unexplained noises, unexplained apparitions, people being pushed and things being moved. The castle is also supposed to be the haunt of two ghosts known as "The Grey Lady", and "The White Lady". The White Lady is supposed to be the ghost of Maria, wife of the 4th Earl; she has been seen sitting in the windows of the castle, and walking the grounds with a white dog. The haunting atmosphere of the castle has inspired at least one gothic "novel" entitled "Elvingstone" by J.P Reedman.