Utilize the input text as a context reference, choose the right relationship between Syriza and Athens from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Even Germany's Wolfgang Schaeuble, who last month floated a Greek exit from the euro as Tsipras hesitated to agree terms with fellow leaders, sounded upbeat, if still wary of a new tone in Athens that caused an angry split in Tsipras' leftist party, with nearly a third of Syriza lawmakers rebelling in parliament.

Answer: headquarters_location