Since at least the 1940s, the Mars Bar (15314 Madison Ave., 216-228-4500) has been a fixture in the Lakewood nightlife ecosystem. George Gountis has been running the joint for the past 13 years, maintaining the bar’s status as a neighborhood staple while making incremental improvements to the grub and setting. The tavern’s gyros have developed their own cult following and the atmosphere is as convivial as it gets.Gountis recently undertook an ambitious expansion project that will more than triple the size of the modestly proportioned saloon. He has taken possession of the adjacent property, once home to Delta Computer, and will connect the two spaces into one large L-shaped property.“This area’s popping right now, and people have really taken a liking to our gyros, so I figured that I’d expand now,” Gountis explains.The additional square footage (3,000) will facilitate the construction of a full kitchen. At lunch, the open counter-style operation will offer walk-up customers a choice of soups, salads and sandwiches like pressed panini. At night, the bar will transition to a full-service tavern with a slightly more creative menu that Gountis describes as “gastropub Mediterranean.” Diners can expect wings, burgers, grilled kebabs, pita pizzas and more vegan and vegetarian options.Mars sells two types of gyros: the traditional lamb and beef variety that arrives in cone form and a weekly special of sliced, house-marinated and stacked pork. Both come with tzatziki sauce that is made by the owner’s mother.When the wall between the spaces is removed, Gountis will extend the bar by about 15 feet into new space. The owner wants to make sure that the bar retains the warm, intimate feel of the old days while accommodating more diners and a fully functioning kitchen. During the warmer months, a covered patio will offer outdoor seating.Gountis hopes to have the project completed before the end of the year.