In an unsurprising move, the biggest and most expensive recent project in the Latvian capital was honored.
Leading the pack of architects was Gunars Birkerts, the primary contracting authority was the Ministry of Culture, and the construction job was conducted by the triumvirate of "Skonto buve", "RBS Skals" and "Re&Re".
While being undoubtedly eye-catching as its vast bulk dominates the skyline of the left bank of the River Daugava, public opinion remains divided about the appeal of the building, particularly when viewed from the Pardaugava side rather than the face presented to the well-heeled Old Town
Riga Mayor Nils Usakovs memorably compared the building to a giant supermarket, but others have been entranced by the soaring grey panels and windows of the so-called 'Castle of Light'.
For the first half of 2015 the building was largely off-limits to the public while it played host to Latvia's European Union Presidency and it regularly holds large-scale conferences within its cavernous interior.
And despite winning the Riga prize, the National Library has been notably omitted from winning the main national architecture award of the year.
Riga Architecture Awards 2015 listed other projects earning an Honorable Mention this year. Among them - the restoration of a classic one-floor wooden dwelling at K.Valdemara St. 45, the modern high rise at Grostonas 19, reconstruction of the dental clinic at Gertrudes 59, and reconstruction of Ward 8, Riga First Hospital at Bruninieku 5.