"Where is the parliament?" A few years ago anyone asking this question in Sofia would have been pointed to a butter-yellow neoclassical building at one end of the Yellow Brick Road. Imaginatively, it resembles the Paris Opera House and has the Belgian national motto, "Unity Makes Strength," above its main façade, looking onto the equestrian statue of a 19th century Russian tsar. This was the place where Bulgarian MPs used to gather to forge this country's laws and regulations.

A person asking the same question today might get a more confusing answer, such as "Which parliament – the old or the new one?" and even "Do you mean the former Party House?". The reason for this confusion stands at the other end of the Yellow Brick Road. There, in a massive tower of grey stone, sits the new home of the Bulgarian National Assembly.

The construction of the Party House, in the early 1950s

The two parliament buildings could not be more different. The old one was built in 1886, at the height of the national enthusiasm in the wake of the previous year's unification of the Principality of Bulgaria and the former Ottoman province of Eastern Rumelia. In the following decades this elegant confection witnessed Bulgaria and its people enduring regional and world wars and transitioning from democracy to authoritarianism to totalitarianism – and back.

The new parliament building appears overbearing and forbidding. It has all the hallmarks of its time as the headquarters of the Bulgarian Communist Party, or the BKP.

Today, significant part of Sofia's traffic passes by the former Party House

Built in 1954, the Party House was a grandiose propaganda piece designed to epitomise the strong grip the Communist Party had over the political, social, economic and even personal life of the citizens of the People's Republic of Bulgaria. Just ten years had passed since the BKP took power, on 9 September 1944, in a Soviet-backed coup, and from there the party managed to deal with both internal and external opposition, to turn the Bulgarian economy upside down, and to transform the country into the USSR's most loyal satellite.

The location of the BKP headquarters was selected for a reason. Beneath it lay the ruins of ancient Serdica and medieval Sredets, indicating continuity. Before construction started, the site had been covered with the remains of pre-war businesses, houses and  hotels destroyed in the 1943-1944 Allied bombing raids. Erecting the BKP's headquarters in such a place conveyed a clear message: Communism in Bulgaria was historically inevitable, the final stage of human evolution, the end of history itself. Resistance to it would be futile.

Due to the concentration of official institutions around the former Party House, including the Council of Minsters and the Office of the President, the area has come to be known as the Triangle of Power

The Party House was also physically distant from the National Assembly, to underline the largely ceremonial role that institution had in Communist Bulgaria.

The architecture of the Party House and the administrative and public buildings of the so-called Largo compound around it was also heavy with symbolism. The so-called Stalinist Baroque style was all about vast empty spaces brooded over by towering buildings with massive colonnades adorned with reliefs of five-pointed stars, sturdy labourers and statuesque farmers and workers. Uniformly grey, with narrow windows that hinted at hidden power, it was meant to induce in passers-by a feeling of helplessness and insignificance in the face of the omnipotent state and the party that controlled it.

The first red star that used to adorn the Party House spire was, until recently, tucked away in a corner of the Museum of Sofia. Now it is in the Museum of Socialist Art. The fate of the second red star, which topped the Party House from 1984 to 1990, is unknown

As the headquarters of the Central Committee of the BKP, the Party House dominated the Largo. It covered more than an acre and had three kilometres of corridors. A red five-pointed star, Kremlin-style, shone from the top of its 70-metre spire. The building was designed to withstand a powerful earthquake and had a bunker, connected by underground corridors to the nearby mausoleum of the Communist dictator Georgi Dimitrov, providing a secure exit for top BKP officials in case of civil unrest.

The coat-of-arms of Communist Bulgaria, along with a hammer and sickle, adorned the façade. There were also more curious details. The corn cobs on the façade, for example, reflected the initiative of Soviet leader Nikita Khrushchev to introduce American hybrid maize to Communist agriculture. The interior decoration was on a par with the exterior: all polished marble, expensive carpets and intricate plaster mouldings.

Stalinist decorations and Communist insignia are still visible on the facade

For the next 35 years the Party House was where Bulgaria's destiny was being hammered – a status made official by Article 1 of the 1971 Constitution that stipulated the "leading role" of the BKP. Few people had access to the inner sanctum of the Communist Party. The only way for ordinary Bulgarians to guess how the in-fighting indoors went on was to read between the lines of the official press, and to take note of which comrade was absent from the Mausoleum patio during the mass rallies on 9 September.

When Communism collapsed following an internal coup on 10 November 1989, the Party House suddenly turned from a mysterious and terrifying centre of power into a lightning rod for public attention and pro-democracy rallies.

The idea to move the Bulgarian parliament into the former BKP headquarters was first mooted in 1995. The old neoclassical building was now considered too small and uncomfortable for the National Assembly administration. After an initial overhaul and  cleaning of the blackened façade, some of the parliamentary administration moved there, in the 2000s. The most blatant Communist symbols were also removed from the façade, including the hammer and sickle and the five-pointed star above the main entrance.

The Sofia Statue that faces the former Party House is on the site where a monument to Lenin once stood. The removed Lenin is now in the Museum for Socialist Art

It was Boyko Borisov's second government (2014-2017) that decided to finally make the big move. A renovation on a grand-scale dragged on for much longer than planned and the costs ballooned from the projected 18 million leva excluding VAT to 44 million leva.

Meanwhile, the main (and never open) entrance of the former Party House became a favourite spot for all kinds of protest rallies. It continues to be so to this day, and if you stay in the area suficiently long you will inevitably witness a rally demanding higher wages for teachers followed by another rally shouting for the re-establsihemnt of the Bulgarian lev, and then yet another rally that demands the immediate termination of the chief prosecutor. Builidngs may have changed, but politics have not.

Tellingly, unlike Khrushchev's corn cobs, the motto "Unity Makes Strength" is missing from the façade of the former Communist Party House, now the new Bulgarian National Assembly. But if you look carefully, the remnants of the five-pointed star are still there.