It was gridlock — caravans of August holiday-makers, plus an overwhelmed European Union border zone — that led my father-in-law to bypass the main Budapest-to-Belgrade highway during the family’s summer road trip.

Whether for reasons of violence, weather or merely traffic, deciding which places to avoid can be as crucial to trip planning as choosing where to go. In this case, a detour through Central Europe turned into a serendipitous journey into Art Nouveau architecture and the poignant loveliness of Austro-Hungarian synagogues.

To drive across these vast, verdant plains is to appreciate how Hungary, a once-mighty country in the Continent’s very heart, ended up with so few major cities. Ethnic Hungarian communities populate metropolises from Slovakia to Romania and beyond, where Habsburgian boulevards are another legacy of a vanished empire.

Szeged, Hungary’s third-largest city, is not very big at all, and its sunny climate, compactness and college-town energy are all seductive. Szeged is famous for being the world capital of paprika, the ruddy, easy-to-love spice that plays a starring role in Hungarian dishes like goulash and chicken paprikash (and makes an ideal souvenir gift).

But paprika is not the only colorful thing about Szeged. Buildings in brilliant red, yellow, orange and turquoise make this corner of Europe a visual delight, with architecture as ornate as the surrounding landscapes are plain. Ancient Szeged — the old stomping grounds of Attila the Hun, according to legend — was destroyed when the Tisza River flooded in 1879, and Emperor Franz Joseph promised to rebuild it as an even more beautiful city.

By all accounts, he succeeded. Exhibit A might be the spectacular, circa-1907 New Synagogue.

The onion-domed Subotica Synagogue. Photos by Wikimedia Commons

Its predecessor, which survived the flood, is situated just minutes away off Hajnócky Street, in Szeged’s old Jewish quarter. The Old Synagogue, now a cultural center, is a white 1840s building in a restrained neoclassical mode.

The New Synagogue, however, is one of Europe’s great Jewish landmarks. It was the second-largest temple in Hungary, after the Great Synagogue of Budapest, when it was built by the renowned Budapest Jewish architect Lipót Baumhorn, and remains one of the greatest anywhere.

Which is why it is so heartening to witness the renovations that are being carried out on this staggeringly beautiful edifice, a fin-de-siècle fantasy of arches and curlicues that one might mistake for a city hall. The blue-and-gold, Moorish-accented interior, lavished with candelabras, a historic organ and a soaring dome, is likewise in the process of renewal — so call ahead before you visit.

There is plenty more to do in Szeged, but time was short, and the inviting café scene has a way of derailing sightseeing plans in a warm haze of coffee, pickles and spicy fish stew.

Just across the border, the signs shifted into Serbian. But the Hungarian influence remained pronounced in the region of Vojvodina, historically the wealthiest and most heavily Catholic part of poor, predominantly Orthodox Christian Serbia.

I had never heard of Subotica (su-BOH-tee-tsa), and once I saw the city’s stunning Art Nouveau architecture, I immediately wondered why; it struck me as no less impressive than the fabled Gaudí buildings of Barcelona, and in a similarly colorful and whimsical vein.

Strolling around central Subotica, another small and pleasant college town, is like wandering a fairy tale. A lot of very important buildings, like the city hall and the synagogue, look like blown-up gingerbread houses, adorned with paprika-red flourishes and Dr. Seussian spires. Roofs, not normally something I notice, catch the eye with arresting tile patterns reminiscent of cross-stitch.

And at least during the warm, golden summer in this famously chilly region, café tables are everywhere. All day long and well into the night, the lively chatter of Serbian college students, Hungarian locals and Croatian tourists gives the plazas and parks the feel of a spontaneous party.

Subotica has played host to a diverse, cosmopolitan populace for centuries, and its sizable Jewish community was active in the 18th through 20th centuries. Today that presence is much diminished, but Subotican Jewish heritage is palpable enough that my husband Oggi wondered whether the city’s Hungarian name, Szabadka (sha-BAHD-ka), had its origins in “Shabbat” (it doesn’t).

Happily, the 1901 Subotica Synagogue, considered a masterpiece of Hungarian Art Nouveau, is also undergoing a badly needed renovation. Its Mitteleuropean majesty makes it a point of pride and history for Vojvodinites; for those road-tripping through Hungarian-inflected Central Europe, it is yet another stunning surprise.

Readers: For a story about overland vs. cruising Alaska, I want to hear about your experience in the land of the Frozen Chosen. Tell me about your trip at hilarasha@gmail.com.