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.

Surrounded by a team of Syriza higher-ups, Lafazanis has stepped up public appearances in Athens and elsewhere in the country that "strongly resemble the start of a campaign", a Syriza member said on condition of anonymity.

Answer: headquarters_location